Gluten Free Chocolate Zucchini Cake

5 from 29 votes

Prep Time : 20

Cook Time : 30

Sneak veggies into everyone's diet when you make this gluten free chocolate zucchini cake recipe. It's so good, no one will know it's gluten free and healthy.

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This gluten free chocolate zucchini cake is simply the richest, most moist chocolate cake ever. What else were you going to do with all that zucchini?

Fork piercing square slice of frosted chocolate cake on small white plate

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What makes this gluten free chocolate zucchini cake special (and so useful!)?

This cake is so rich, with deep chocolate flavor, and the zucchini keeps every dense, rich bite moist and tender without being “fluffy.”

Every solid recipe using at least a few cups of shredded zucchini is nothing short of a public service. Take this gluten free chocolate zucchini cake, for example.

It tastes approximately, well, nothing like zucchini. The garden veg is just a delivery system for moisture in each morsel of cake.

Unlike in our gluten free zucchini bread, you won't even see the zucchini in this dark brown cake. Plus, the fudge frosting on top is a nice bonus, especially since you won't believe how easy it is to make a chocolate frosting without powdered sugar!

The best gluten free chocolate zucchini cake recipe? Definitely!

This one bowl chocolate zucchini cake is super easy to put together with dry ingredients whisked, then wet ingredients added and mixed
It has incredible texture and taste, making for a rich chocolate cake with only cocoa powder, no melted chocolate in the batter.
A healthy chocolate zucchini cake is an easy way to sneak in veggies, since you won't taste the zucchini at all
Finally, no one will know it's gluten free, if they have that thing where they think that gluten free cakes are “only okay.”

Raw chocolate zucchini cake batter in metal bowl with black spatula

Recipe ingredients

Fresh zucchini – This cake makes use of 3 whole cups of fresh grated zucchini!
Gluten free flour – I prefer Better Batter (always their classic rice flour-based blend) here, and be sure to measure by weight, not volume, for reliable results
Unsweetened cocoa powder – I use Dutch-processed cocoa powder, which is treated to neutralize the natural acid in natural cocoa powder; if you use natural cocoa powder, just add 1/8 teaspoon baking soda to rebalance. For a sweet zucchini recipe without the cocoa powder, try our gluten free zucchini bread.
Salt – Brings out flavors and balances the sweetness
Baking powder – A chemical leavener that is responsible for most of the rise in the cake
Granulated sugar – A sweetener and a tenderizer; don't cut back as it's not an especially sweet cake at all!
Light brown sugar – A sweetener and tenderizer, like granulated sugar, but adds depth of flavor and moisture from the molasses added to it
Oil – The fat in this recipe is from a neutral, flavorless oil, that, together with cocoa powder, creates that deep chocolate flavor and mouthfeel
Eggs – Eggs help bind the ingredients together and aid in the cake's rise; yolks provide richness
Vanilla extract – Bring out the chocolate flavor and adds depth

Raw chocolate zucchini cake batter in square baking pan

Baked chocolate zucchini cake in square baking pan

What you need to make this healthy chocolate cake recipe

You don't need much equipment at all to make this zucchini cake. Beyond the ingredients in the recipe, the only equipment you need is:

Mixing bowl and spoon
Whisk to combine dry ingredients (or just a fork)
9-inch square (or round) baking pan
Parchment paper to line the pan
Spatula to scrape the batter into the baking pan and smooth it into an even layer
An oven for baking

Recipe tips

Don't try to substitute the gluten free flour blend

When we're baking gluten free with an “all purpose gluten free flour blend,” the blend always matters. I use and recommend Better Batter here, but any of the blends I discuss as all purpose gf blends on the blog (click that link in the previous sentence or in the recipe card where the flour blend is referenced) will work.

Don't try using a single-ingredient flour, such as almond flour or coconut flour, as they only work in recipes that are designed to be made with them.

Shred your zucchini to a standard grate size

I find shredding zucchini to be easiest using a standard box grater, ideally one with a lid on the bottom, so it catches the shreds. Use the “coarse shred” size, which is usually the side of your grater with the largest repeating hole (as opposed to the slicer).

You can also shred your zucchini using a a food processor fitted with the shredder blade. If you're going to use a food processor, then shred tons of zucchini, and store leftover in a freezer-safe zip top bag. Defrost, and bake!

Box grater with partially grated zucchini

Drain your zucchini of its liquid

Be sure to squeeze as much of the surface moisture from your shredded zucchini as you can. You can do this using a mesh nut milk bag or a tea towel (a kitchen towel with a flat weave)—just pile in the shredded zucchini and squeeze over the sink.

There will still be some moisture inside the vegetable, but since the amount of moisture in the vegetable can vary so much, squeezing out the moisture is the only way to make sure we're all using the same ingredient.

Bake your gf zucchini cake on the middle rack

For even baking, and don't forget to preheat your oven and gauge your oven's temperature using a standalone oven thermometer that you replace frequently. Most ovens, including mine, run hot and out of calibration, which causes cakes to puff and then fall as they cool since they're underbaked in the center.

Don't overbake to keep your chocolate zucchini cake moist

This is a very moist, tender gf cake, so your cake tester inserted in the center won't come out completely clean. Test doneness as described in the recipe: when the center of the cake springs back when pressed gently in the center and a tester comes out with a few moist crumbs attached.

Let your gf chocolate zucchini cake cool completely before frosting

Frosting a warm cake will cause your frosting, or even a light dusting of powdered sugar, to melt right into the cake. You'll still taste the topping, but you won't see it—and it will lose its texture.

Fudge frosting on end of metal spatula and in glass jar

How to make the chocolate fudge frosting

This chocolate frosting is completely optional here, but it's such a good choice—and stays fresh in a sealed glass jar on the countertop for days. It's made entirely without any sort of confectioners' or powdered sugar, which makes it a nice option for a quick, fuss-free frosting. And it's just so glossy and smooth!

All you do is blend granulated sugar with evaporated milk (not sweetened condensed milk, and just 2/3 cup, so you won't need a whole can of evaporated milk) to dissolve the sugar and ensure the frosting isn't grainy. Then, melt 4 ounces of chopped chocolate, and 4 tablespoons of unsalted butter, and blend them right in.

As you blend, the frosting will thicken to a thick pudding-like consistency, like magic. You'll know the frosting is ready when you can turn your blender upside down and it won't move.

More serving suggestions

I’d like to recommend that you enjoy a slice of this crazy delicious gluten free chocolate zucchini cake with some summer berries, like strawberries.

Since you’re only likely to be making this particular gluten free chocolate cake in the summertime, you should go all the way. Here are some more suggestions:

Try a different frosting, like strawberry sauce or cream cheese frosting;
Make a healthy birthday cake with frosting and colorful sprinkles
Dust lightly with with powdered sugar after the cake is completely cool, and serve with a dollop of fresh whipped cream
Replace the chocolate chips with a different flavor of chips, like butterscotch or peanut butter chips (just be sure your brand is GF).

Storage instructions

In testing this recipe, I made it so many times that I had an enormous backlog of cake in my kitchen. I ended up storing it, cut into bite-sized pieces, in sealed containers on the countertop for a full week. And it was only just beginning to taste a little dry on day 6.

Can I freeze gluten free chocolate zucchini cake?

Yes! For longer storage, you can freeze the whole, unfrosted cake, or freeze individual slices. Just wrap each tightly in freezer-safe wrap to avoid freezer burn, and defrost at room temperature. Frost before serving.

Ingredient substitutions

Whenever I can, I like to provide you with as much information as possible on modifying this recipe to suit all of your individual dietary needs. These are educated guesses, though, since I haven’t actually made this recipe successfully in any way other than as it’s written in the actual recipe below.

Dairy free

The only dairy in the cake recipe is the buttermilk. If you're dairy-free, you can replace dairy buttermilk with a combination of half plain nondairy yogurt (by volume) and half unsweetened nondairy milk (by volume).

If you can have dairy, and you're out of buttermilk or just don't want to buy it, try using plain kefir or the half-plain-yogurt-half-milk trick, just with dairy products.

The fudge frosting on top is made with evaporated milk and butter, though. If you're dairy free, you can leave the fudge frosting out, or try using coconut evaporated milk (Nature's Charm is the brand I've seen) and vegan butter (Melt and Miyoko's Kitchen brands are my favorite).

If you're dairy-free, be sure that the chocolate chips and bittersweet chocolate you’re using are dairy free.

Egg free?

Since this recipe calls for 3 whole eggs, which is in dangerous territory for replacing eggs (my upper limit for egg replacement is usually 2). But it's worth trying one “chia egg,” which is just a tablespoon of ground chia seeds mixed with 1 tablespoon of cool water until it gels per chicken egg.

One chia egg per actual egg, please. No flax eggs, though, please, which adds an unwanted flavor.

Vegan

Use the dairy free and egg free suggestions above, and use vegan sugars, made without use of bone char.

Chocolate free?

If you’d like a plainer version of this cake, without chocolate, there really isn’t a substitute for the chopped, melted chocolate and cocoa powder.

Instead, I have a recipe for gluten free zucchini cake with the most tender texture—and it’s kind of a blank canvas for other flavors. Try it with the cream cheese frosting recipe in that link.

FAQs

Why should I add zucchini to chocolate cake?

Zucchini adds lots of moisture to cake, tenderizing the crumb and ensuring a softness that you can't beat. It also adds some fiber, which makes this a healthier cake than some.

Can you taste the zucchini?

No! The flavor of zucchini, even if you love it, would seem out of place in a sweet cake. This recipe has no zucchini flavor at all.

Is this a flourless chocolate zucchini cake recipe?

No! This cake is more of a “regular” gluten free cake, made with an all purpose gluten free flour blend. The zucchini doesn't replace the flour, like the quinoa does in our quinoa chocolate cake or like melted chocolate does in our flourless chocolate cake.

Is this recipe for chocolate zucchini cake good for making a layer cake?

No, I don't recommend making this as a layer cake, since it's so incredibly moist that it doesn't slice that cleanly. It's best sliced into rustic squares, as a single layer cake.

Can I use this zucchini chocolate cake recipe to make cupcakes?

I haven't tried this recipe as cupcakes, and I find that the best cupcakes call for dedicated cupcake recipes. If you decide to try baking the batter in muffin tins, please let us know how it turns out!

How to make gluten free chocolate zucchini cake

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Sneak veggies into everyone's diet when you make this gluten free chocolate zucchini cake recipe. It's so good, no one will know it's gluten free and healthy.

Course: Cake, Dessert

Cuisine: American

Prep Time: 20

Cook Time: 30

Yield: 1 9-inch cake

Author: Nicole Hunn

Ingredients

For the cake

1 ½ cups (210 g) all purpose gluten free flour blend (I used Better Batter; please click thru for appropriate blend info)
¾ teaspoon xanthan gum omit if your blend already contains it
½ cup (40 g) unsweetened cocoa powder Dutch-processed preferred (if using natural, add 1/8 teaspoon baking soda)
½ teaspoon kosher salt
1 ½ teaspoons baking powder
¾ cup (150 g) granulated sugar
3 tablespoons (41 g) packed light brown sugar
2 ¾ cups (170 g) shredded zucchini (from about 2 large or 3 medium zucchini) drained of liquid (See Recipe Notes)
6 tablespoons (84 g) neutral oil (vegetable, canola, grapeseed, or peanut oil all work fine)
1 teaspoon pure vanilla extract
3 (150 g (weighed out of shell)) eggs at room temperature, beaten
9 tablespoons (4.5 fluid ounces) buttermilk at room temperature
4 ounces chocolate chunks or chips (optional)

For the fudge frosting

⅔ cup (5 ⅓ fluid ounces) evaporated milk
1 cup (200 g) granulated sugar
4 ounces bittersweet chocolate melted
4 tablespoons (56 g) unsalted butter melted

Instructions

Make the cake.

Preheat your oven to 350°F. Grease and line a 9-inch square baking pan and set it aside.
In a large bowl, place the flour, xanthan gum, cocoa powder, salt, baking powder and granulated sugar, and whisk to combine well.
Add the brown sugar and mix to combine, breaking up any lumps in the brown sugar and in the cocoa powder.
Add the shredded zucchini, and mix to combine until the zucchini is fully coated in the dry ingredients.
Create a well in the center of the mixture and add the oil, vanilla, eggs, and buttermilk. Mix to combine (the mixture will be thick but soft).
Add the optional chocolate chips, and mix until they're evenly distributed throughout the cake batter.
Transfer the batter to the prepared baking pan and spread it into an even layer with a spatula.
Place the pan in the center of the preheated oven and bake for about 30 minutes.
The cake is done when the cake springs back when pressed gently in the center with a finger, and a toothpick inserted in the center comes out with a few moist crumbs attached.
Remove the cake from the oven and allow to cool in the pan for at least 20 minutes before slicing or frosting it.

Make the fudge frosting (optional).

Place evaporated milk and sugar in a blender and blend for at least 1 minute, or until the sugar is dissolved.
Add the melted chocolate and butter to the mixture in the blender, and blend for about another 1 minute, or until the mixture thickens to a pudding-like consistency.
Store the frosting at room temperature in a sealed container until ready to use.

Serving suggestions

Spread the fudge frosting on the cooled chocolate zucchini cake, slice into squares with a serrated knife, and serve.
Alternative serving suggestion: Slice the cooled cake into squares with a serrated knife, and spread frosting on each slice right before serving.

Notes

How to prepare the shredded zucchini.

To drain zucchini of its moisture, shred it on a standard-size box grater, then place it in a tea towel, wrap the towel around the zucchini, and squeeze with your hands until the zucchini is no longer wet to the touch and forms clumps.

You can prepare the zucchini about 1 week ahead of time, and store it in a well-sealed zip top bag in the refrigerator. Let it come to room temperature before baking with it.

How much zucchini you will need.

You'll begin with about 300 grams of shredded fresh zucchini, but the important thing is that your cake have 170 grams of drained zucchini. Some zucchini begins with more moisture, so you'll need to begin with more zucchini to get 170 grams of it fully drained of moisture.

Fudge frosting recipe adapted from Taste of Home.

Originally published on the blog in 2013. In 2022, recipe simplified and cake made more tender; fudge frosting new; photos, video and text mostly new.