Gluten-Free Green Bean Casserole Recipe

For a gluten-free version of a classic green bean casserole, replace the canned soup and fried onions with homemade.

Elizabeth Barbone

A few years ago, when one of my readers asked me to create a gluten-free version of Campbell's green bean casserole, I was excited. Until then, I had never eaten the classic Thanksgiving side. After perfecting the recipe, a funny thing happened: several of my friends revealed themselves to be secret green bean casserole lovers. Now I make this for Thanksgiving every year. Another huge part of the tradition is munching on the freshly fried onion strips.

Created by Campbell's in 1955, the original recipe uses canned green beans and canned cream of mushroom soup. While de-glutening the recipe, I replaced the canned green beans with frozen because I prefer the texture. (And if fresh green beans had looked good at the market, I would have used those. That said, if you love canned green beans in this dish because that's how you've always made it, use them!)

The canned soup had to go, of course, because it isn't gluten-free. It's replaced with an easy-to-make white sauce and chopped mushrooms. During recipe development I wanted to stay true to the original and not tinker with the flavors too much. Since cream of mushroom soup isn't aggressively mushroom flavored, I used white button mushrooms in the sauce. They do a great job of letting you know they're there but not shouting at your tastebuds. (If you'd like to use a more flavorful mushroom, go for it. This dish welcomes interpretation.)

The last canned good to go was the canned french fried onions. (Which I noticed this year are no longer in a can but rather in a plastic tub.) This is my favorite part of the casserole (anyone else?). I usually double (cough, triple it, cough) because I we eat so many before topping the casserole.

To make Thanksgiving prep a little easier, you can make the casserole the night before. (Don't top it with the fried onions the night before or they'll get soggy.) About 30 minutes before you are ready to serve, heat the casserole in the oven and then top with the freshly fried onions.

Recipe Facts

Active: 40 mins
Total: 60 mins
Serves: 6 servings

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  • For the Fried Onions:
  • 3 tablespoons cornstarch
  • 3 tablespoons white rice flour
  • 1 medium onion, sliced into thin strips
  • For the Casserole:
  • Vegetable oil for frying
  • Salt, to taste (optional)
  • 3 tablespoons olive oil, divided
  • 1 small onion, finely diced
  • 8 ounces white button mushrooms, finely chopped (approximately 3 cups)
  • 1 clove garlic, minced or put through a garlic press
  • 2 cups milk, divided
  • 2 tablespoons cornstarch
  • 1 (16-ounce) bag frozen French-cut green beans, thawed and drained or 16-ounces fresh green beans, cleaned, trimmed, and cooked until tender
  • 1/8 teaspoon ground thyme
  • Salt and pepper, to taste
  • 1/4 cup grated Parmesan cheese, divided


  1. For the Onions: In a large zip-close bag, combine cornstarch and white rice flour. Add onions and shake bag to combine. Remove onions from bag; shake off any excess flour.

  2. Fill a large heavy-bottomed skillet (cast iron works best) with 1/2 inch of vegetable oil. Heat oil over medium-high heat until hot and shimmering. (To test your oil, drop one onion slice into it. The onion should sizzle when it hits the oil. If it doesn't, the oil is not hot enough.) Fry a handful of onions, about 4- 5 batches, until golden brown and crispy. (Don't crowd the pan while frying.

  3. Remove onions from oil using a slotted spoon. Place on paper towel-lined plate to drain. If desired, season with salt to taste. Repeat with remaining onions.

  4. For the casserole: Preheat oven to 350oF. In a medium saucepan, heat 2 tablespoons of olive oil over medium-high until shimmering. Add onion and garlic. Sauté until soft, stirring frequently. Add mushrooms and remaining tablespoon of olive oil. Cook until mushrooms are soft and tender, stirring frequently, about three minutes.

  5. Add 1 3/4 cups of milk and thyme. Bring to a boil. Once the mixture boils, combine remaining 1/4 cup of milk and two tablespoons cornstarch. Stir vigorously with a fork to combine milk and cornstarch. Quickly whisk in cornstarch. Allow to boil for 45 seconds. Remove from heat. Reduce heat to low. Allow to simmer for three minutes. Salt and pepper to taste.

  6. Add green beans, stir to combine. Pour into a 1 1/2-quart casserole dish. Top with half the grated Parmesan cheese. Cover with foil. Bake for 30 minutes.

  7. Remove foil. Sprinkle fried onions and remaining cheese over the top of casserole. Return to oven until bubbling and lightly golden brown, about seven minutes.