Easy Gluten Free Green Bean Casserole (No Canned Soup!)

The secret to the perfect gluten free green bean casserole is layers of simple, rich flavors that combine to make the simple side dish everyone knows with a surprisingly complex flavor no one expects.

With crisp-tender green beans, rich, flavorful mushroom soup, a touch of Parmesan cheese and with perfect crispy onions, your guests will be asking for the recipe!

Why this recipe works

If you've had green bean casserole at your holiday table for years only for the sake of tradition, this is the dish that breaks the mold. We keep this popular side as simple as ever, but add multiple dimensions of flavor that enhance each other one layer at a time.

We begin with the best fresh green beans boiled only long enough to bring out their natural sweetness. Then, combine them with our easy homemade mushroom soup that's packed with umami flavor, add just enough grated Parmesan cheese, and top with sautéed mushrooms and buttery bread crumbs.

We only add sweet and crunchy fried onions at the very end after baking the dish, to avoid changing their already-perfect airy, crispy texture.

Ingredients explained

There are only a few ingredients in this recipe. Here's a bit about the role of each one in the final green bean casserole:

• Green beans: Fresh whole green beans are best here, but you can use frozen, too. When buying fresh, avoid the prepared bagged kind that's already washed and pre-cut. No matter where I buy them, they tend to smell a bit like glue, and are often slimy and moldy—plus ridiculously expensive.
• Gluten fee cream of mushroom soup: Adds moisture to bring the dish together, a creamy texture, and so much deep, rich flavor. You can make your own gluten free cream of mushroom soup up to 1 week ahead of time, and store it in the refrigerator. Or buy one of the many available packaged brands we discuss below.
• Sautéed mushrooms: Add slightly chewy, tender texture and lots of flavor. For the most flavor, use baby bella mushrooms. If you're making homemade soup, you'll end up with half of the 1 pound of mushrooms in the recipe blended into the soup, and rest whole.
• Gluten free bread crumbs: Be sure you're using coarse, Panko-style breadcrumbs, which add a crunchy texture to the top of the casserole with or without fried onions. I like Nature's Promise brand, which is a Stop & Shop house brand, and but Ian's gluten free brand is also excellent. You can always make your own gluten free breadcrumbs, too.
• Grated Parmesan cheese: Adds a ton of complex umami flavor to this simple dish. I prefer to grate my own Parmigiano-Reggiano cheese, but the store-grated kind is great, too. I'd avoid the shelf-stable stuff, though, as it just doesn't have much flavor.
• Crispy fried onions: Add lots of sweet-savory flavor and an unmistakable crispy texture. You can leave them out, or replace them with crispy shallots, fried garlic, or even just more breadcrumbs.

How to make gluten free green bean casserole (step by step photos)

The full ingredient amounts and instructions are in the recipe card below. Below are step by step photos to guide you in your own kitchen, with explanations for each:

1. Prepare the ingredients

There are so few ingredients in this recipe, but two to three of the main ingredients require some advance preparation:

• Green beans: Clean your fresh green beans by cutting off at least the end of each bean that was attached to the vine, which is usually a bit stale. Rinse them well in water, drain, and place them in boiling water for 3 minute, or until very bright green. Drain, and blot dry to avoid adding extra water to the dish, making it watery.
• Cream of mushroom soup: If you're making this from scratch, let it cool to room temperature before combining with the beans so it doesn't cook them. If you're not making homemade soup, sauté 8 ounces of sliced baby bella or white mushrooms in butter or olive oil with a pinch of salt and pepper over medium-low heat until they soften, about 5 minutes.
• Crispy fried onions: If you're making these from scratch, there's really no rush since you only layer them on right before serving. But it does take some time to fry them, so plan ahead.

2. Make the filling & layer

Once the green beans, soup and sliced mushrooms are properly prepared, the assembly is easy. Combine the beans with the soup and half of the grated cheese, and place in an even layer in a prepared casserole dish.

Layer the sautéed mushrooms on top, and sprinkle with half of the remaining grated cheese.

In a small mixing bowl, mix the coarse breadcrumbs with melted butter until all the crumbs are moistened.

3. Bake

Layer on the buttery breadcrumbs, then all of the remaining grated cheese. Since everything is mostly cooked, bake only to warm the ingredients together, and brown the breadcrumbs and cheese mixture on top. At 375°F, that takes about 15 minutes.

4. Add crispy onions

Right after baking, sprinkle crispy onions in an even layer on top of the browned breadcrumbs and cheese. Press down gently to help the onions adhere at least a bit, so they don't fall right off. We don't bake the onions because we don't want to change their texture at all. They add the perfect salty, flavorful crunch just as they are.

Expert tips

Slice the green beans carefully

Slice the ends in one motion with a sharp knife to create a clean edge, which will help them absorb the sauce without wilting. On very fresh beans, I only slice off the end that was attached to the vine, since the other end is pretty and hasn't been exposed yet so it hasn't oxidized.

Make the recipe in stages

To make preparation as easy as possible, I recommend making the individual parts of this recipe (cooking the mushroom soup, cleaning the green beans, grating the cheese, if you're using any) ahead of time, and storing them in the refrigerator. Just be sure to let them come to room temperature before combining them, so the soup and cheese combine fully without clumping.

Don't overbake

This recipe spends very little time in the oven. In fact, it's baked mostly to make the mushroom sauce nice and bubbly, help the flavors combine, and to brown the breadcrumb topping—but not to cook the green beans much. If you overcook the green beans, they'll be mushy.

Use fresh beans when possible

If you can buy fresh bright green, firm and uncut green beans at your grocery store, those are the best. They'll have just the right naturally sweet flavor and snappy freshness that is enhanced by quickly blanching them in boiling water.

If fresh aren't available, use frozen whole green beans. Pick a bag from the store that seems like it's less icy, and defrost them at 50% power in a microwave oven or even overnight in a bowl in the refrigerator. Drain any liquid remaining, blot them dry, and proceed with the recipe as written. Do not boil them because they're already blanched.

If you only have canned green beans, warm the soup on the stovetop without the green beans first. Then, assemble everything, including the green beans, and bake the casserole as little as possible, just until the other ingredients are warm, not hot. Otherwise, the beans may turn mushy.

Ingredient substitutions

Dairy free

To replace the dairy in this dish specifically, use vegan butter for the topping (Melt and Miyoko's Kitchen brands are best), and omit the grated cheese entirely. I recommend adding up to 1/2 cup nutritional yeast in place of cheese for added flavor, unless you really don't like its flavor.

To make the gluten free cream of mushroom soup without dairy, please see the ingredients and substitutions section of that post. If you're making homemade crispy fried onions, in place of buttermilk for soaking, use half nondairy milk and half plain nondairy yogurt.

Onion free

Make the cream of mushroom soup recipe without shallots, and add a bit of gluten free tamari or soy sauce for more flavor.

For the onion topping, leave it off entirely and add some extra finely grated Parmigiano-Reggiano cheese to the top of the buttered gluten free bread crumbs. For some added crunch, add crushed gluten free potato chips, crushed gluten free crackers, or even crushed gluten free pork rinds.

Ingredient shortcuts

There are so many brands that make good, reliable gluten free cream of mushroom soup and crispy onions these days. They're great when you're short on time or just can't be bothered making them fresh. Here are some of my favorites:

Gluten free mushroom soup brands

These are the brands that I have tried that make their own version of gluten free cream of mushroom soup:

• Pacific Foods makes a cream of mushroom soup with whole ingredients, and thickened with cornstarch and rice flour. It's marked gluten free.
• Campbell's brand makes a gluten free cream of mushroom soup with soy protein concentrate, thickened with cornstarch and rice flour. Be sure you choose the can that has the orange circle on it that says “gluten free.”
• Imagine brand makes a creamy portobello mushroom soup with whole ingredients, thickened with tapioca starch; it's thinner than the canned condensed soups, so you’ll need to simmer it on the stovetop to reduce it.

Gluten free crispy onions brands

You can make your own gluten free crispy fried onions, but to be honest I usually buy one of the excellent store brands. Here are some of my favorites:

• Trader Joe's sells crispy shallots made without any flour at all, just shallots and oil. They also now sell fried, sliced garlic.
• Store brands from stores such as Aldi, Sprouts, and Shop Rite are often a great source of gluten free can of French fried onions. It appears that the organic offering is often also gluten free. For example, Organics brand is a quasi-generic owned by Albertson's, so you can find them at all store they own, including Acme, Safeway, Balducci's.
• Root is a newer brand of fried vegetable chips. I love their sliced, “flash-crisped” crunchy texture, and their multi-colored onion chips are a great substitute for classic crispy fried onions.
• Amazon: Nawabi Life brand is another option that you can get quickly with Prime shipping. Sometimes, you can find other options on the site, but it's hit or miss.

FAQs

Prepping in advance

You can combine the cream of mushroom soup with the blanched green beans, add the optional cheese, and place it in the prepared casserole dish. Seal the dish well, and store it in the refrigerator for up to 2 days ahead of time.

You can also just make the cream of mushroom soup recipe ahead of time, and store that, and the reserved mushrooms, in well-sealed glass jars in the refrigerator for up to a week. You can also store the blanched green beans in a sealed container for up to 2 days.

Storage suggestions

The fully prepared dish, with crispy onions at all, is best fresh. If you think your dinner guests or family members may not eat a whole recipe in one sitting, or you're eating alone, I recommend cutting the whole recipe in half—or even down to ⅓.

If you do have leftovers, try as best you can to remove the crispy onions from the top, and store those separately. The moisture from the rest of the dish will rob them of their crispiness. Place the rest of the dish in a sealed plastic or glass container and store in the refrigerator for up to 5 days. Sprinkle lightly with water and reheat in a single layer in an oven-safe dish at 300°F until warm.

Serving suggestions

Green bean casserole is a gluten free Thanksgiving holiday staple. So you'll usually find it served along with the best gluten free stuffing or make a big bowl of gluten free mac and cheese recipe with some roasted turkey or chicken. For extra onion flavor, season the bread crumbs with some gluten free onion soup mix before adding the melted butter.

You might also make a half batch, if it's not for a holiday, and serve it as a side to gluten free chicken cutlets. I've even served it with a gluten free quiche for a simple meatless dinner.