This light and fluffy gluten free sweet potato casserole filling is topped with a sweet, nubby crumble topping that everyone loves.
How sweet is this sweet potato casserole?
When most Americans think of sweet potato casserole, it brings to mind a filling made of boiled sweet potatoes with plenty of added sugar. And, of course, a dense marshmallow topping.
I didn’t grow up eating that sort of sweet potato casserole, so it has no nostalgic value for me. If it does for you, I promise I’m not throwing any shade on that dish!
But if you were like me in assuming there was no way to make a sweet potato casserole that would be better than just puréed and roasted sweet potatoes, with maybe a touch of milk, this recipe is for you (us).
There is a bit of sugar in the filling, but only 1/4 cup in a filling made with 4 pounds of roasted and peeled sweet potatoes. It’s just enough to lightly sweeten the other ingredients we add to the filling, but not so much that the filling tastes sweetened.
And oh, that crumble topping…
The topping is made with two different types of sugar, and plenty of butter. It isn’t healthy and doesn’t even pretend to be good for you.
But the nubbiness of the mixture holds its shape during baking just like it does on a coffee cake. But it’s a thinner layer, with lots more cinnamon.
It is sweet, but it’s also toasted and crunchy. So it adds the most amazing texture variation to that pillow-soft sweet potato filling.
How to prepare the sweet potatoes
Rather than peeling, chopping, and boiling or steaming the sweet potatoes for the filling in this sweet potato casserole, I always roast them in their skins. Roasting sweet potatoes intensifies their natural sweetness and even caramelizes some of it.
The result is a much more complex flavor that retains all of its flavors (and nutrients), unlike boiling which draws many of the nutrients out into the boiling water.
The skin of a sweet potato is very thin, and becomes paper-like when it’s roasted. I bet you could even purée the sweet potatoes with their skins, rather than removing them for the filling.
Can the sweet potatoes be made ahead of time?
Yes, you can definitely roast the sweet potatoes ahead of time. In fact, preparing the sweet potatoes is the first thing you should do, and can be done days ahead of time.
To roast them, wash them well with running water, then dry them thoroughly. Pierce through the skin of each all over the with the tines of a fork, and wrap it separately in aluminum foil.
Place the wrapped sweet potatoes on a rimmed baking sheet and roast in a preheated 375°F oven until a paring knife inserted in the center of the thickest part of each sweet potato doesn’t encounter any resistance (45 minutes to 1 hour+, depending upon size).
Remove the sweet potatoes from the oven, unwrap them, and allow them to sit until they are cool enough to handle. Remove the skins (they should slip or peel right off), and set them aside to use in the filling recipe.
Ingredients and substitutions
There is dairy in both the crumble topping and the filling, but they should both be replaceable. I’d use vegan butter in each.
My favorite brands of vegan butter are Melt and Miyoko’s Kitchen. You could also use Earth Balance buttery sticks in the filling, but not in the crumble topping as it won’t hold its shape properly during baking.
In place of the dairy milk in the filling, you can use any nondairy milk you like. I recommend using something unsweetened and unflavored, like unsweetened almond milk.
I don’t recommend trying to replace the eggs in this recipe. There are 4 whole eggs, which is too many to attempt to replace with any egg replacer. Sorry!
“Purity protocol” gluten free oats are safe to eat, but if you avoid them anyway, you can replace them. The oats in the crumble topping recipe with 1/4 cup (35 g) additional all purpose gluten free flour (for a total of 1 cup (140 g).
For a complete discussion of substitutions for oats in gluten free baking, please see our substituting oats guide.
Gluten Free Sweet Potato Casserole
For the filling
4 to 5 pounds sweet potatoes (5 to 6 large), roasted and skins removed (See Recipe Notes)
1/4 cup (50 g) granulated sugar
1/4 teaspoon kosher salt
1/2 cup (4 fluid ounces) milk
4 eggs (200 g, weighed out of shell), lightly beaten
5 tablespoons (70 g) unsalted butter, melted and cooled
1/2 teaspoon vanilla extract
For the crumble topping
3/4 cup (105 g) all purpose gluten free flour (I used Better Batter)
Scant 1/2 teaspoon xanthan gum (omit if your blend already contains it)
1/4 cup (25 g) certified gluten free old-fashioned rolled oats (See Recipe Notes)
1/4 cup (55 g) packed light brown sugar
1/4 cup (50 g) granulated sugar
1 1/2 teaspoons ground cinnamon
1/8 teaspoon kosher salt
6 tablespoons (84 g) unsalted butter, melted and cooled
To roast the sweet potatoes
Preheat your oven to 375°F. Wash and dry the raw sweet potatoes, then pierce all over with the tines of a fork. Wrap each separately in aluminum foil, place on a rimmed baking sheet, and bake until a paring knife inserted in the center of the thickest part of each sweet potato doesn’t encounter any resistance (45 minutes to 1 hour+, depending upon size). Remove the sweet potatoes from the oven, unwrap them, and allow them to cool until you’re able to handle them.
Once roasted and skinned, your sweet potatoes should weigh at least 3 1/2 pounds. Keep that mind as you select the number of sweet potatoes you will prepare.
About the gluten free oats
So-called “purity protocol” gluten free oats are safe to eat, but if you avoid them anyway, you can replace the oats in the crumble topping recipe with 1/4 cup (35 g) additional all purpose gluten free flour (for a total of 1 cup (140 g).
About the food processor
If you only have a small food processor, purée the sweet potatoes in batches, and then mix everything together in a large bowl. If you don’t have a food processor, I’ve made the filling with a hand mixer, but it’s just not as smooth.
First, preheat your oven to 375°F and roast the sweet potatoes according to the instructions in the Recipe Notes. As they roast, prepare the topping, which will need to chill.
To make the crumble topping, in a medium-sized bowl, place the flour, xanthan gum, oats, brown sugar, granulated sugar, cinnamon, and salt, and whisk to combine, working out any lumps in the brown sugar. Add the melted butter, and mix to combine well. The mixture will be thick. Place the bowl in the refrigerator to chill for at least 10 minutes or until firm.
Reduce the oven temperature to 350°F. Grease a 9-inch x 12- or 13-inch baking dish and set it aside.
In the bowl of a food processor fitted with the steel blade (See Recipe Notes), place the sweet potato flesh and process for about 2 minutes. With the food processor still working, add the remaining ingredients (granulated sugar, salt, milk, eggs, butter, and vanilla) through the shoot and process until smooth. Stop the food processor as necessary to scrap down the sides and keep the mixture moving. The filling will be thick but very soft and smooth.
Transfer the filling to the prepared baking dish, and smooth the top into an even layer. Remove the crumble topping from the refrigerator, break it up into irregular pieces with the tines of a fork, and sprinkle the pieces evenly over the top of the filling.
Place in the center of the preheated oven and bake until the topping is golden brown and the filling appears set (about 45 minutes). Allow the dish to cool completely before serving.