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make-ahead green bean casserole in baking dish

Make-Ahead Green Bean Casserole

Make-Ahead Green Bean Casserole is made with fresh green beans and a homemade cream-of-mushroom soup that is delicious enough to be eaten on its own. It can be made in advance up to (but not including) the topping. It freezes well, so how far in advance you want to make the dish is up to you. If you’re making this for Thanksgiving, simply pop it in the oven when the turkey comes out and let it bake while the bird rests.
Course Side Dish
Cuisine American/Comfort Food
Keyword green bean casserole, thanksgiving dinner
Prep Time 15 minutes
Cook Time 1 hour 30 minutes
Total Time 1 hour 45 minutes
Servings 10 -12
Author Michelle



  • 3 tablespoons unsalted butter
  • 8 ounces fresh cremini mushrooms cleaned, trimmed, and roughly chopped
  • 1 teaspoon kosher salt
  • 1/2 teaspoon black pepper
  • 6 cloves garlic minced (don’t skimp on these!)
  • 1/2 teaspoon dried thyme
  • 1/4 cup flour
  • 1/2 cup dried mushrooms preferably porcini, rehydrated
  • 1 1/2 cups of mushroom-rehydrating liquid strained; you can mix with chicken stock (the proportion to make 1 1/2 cups is up to you)
  • 1/2 cup dry white wine
  • 1 1/2 cups cream
  • 1 tablespoon sweet marsala optional
  • Additional kosher salt and freshly ground black pepper if needed


  • 2 pounds fresh green beans preferably haricots verts, stems trimmed, snapped into bite-size pieces
  • 1/4 cup cornstarch


  • 1 cup panko breadcrumbs
  • 2 tablespoons melted butter
  • 1/2 teaspoon kosher salt
  • Freshly ground pepper
  • 2 cups canned fried onions* coarsely chopped



  • Rehydrate dried mushrooms in 1 1/2 cups of scalding water for at least 30 minutes. Strain the mushroom rehydrating liquid into a measuring cup and mix (as needed) with broth to make 1 1/2 cups. Remove the rehydrated mushrooms and rinse. Chop finely.
  • Blanch the green beans by boiling them 3-5 minutes, until still crisp-tender. Drain and plunge into a large bowl of ice water. When cooled, drain and pat dry with paper towels.
  • Meanwhile, in a heavy-bottomed pot, melt the butter over medium heat. Add the mushrooms, salt, and pepper. Cook, stirring frequently, until the mushrooms have given up their liquid. Continue cooking until liquid is evaporated. Add the garlic and thyme; cook for ~1 minute more. Sprinkle flour over the mixture; stir to combine. Slowly stir in the rehydrating liquid (a tablespoon at a time), allowing each addition to absorb completely before adding more. (This will prevent lumps, so be patient!) Stir in the cream and wine; bring to a boil. Simmer, stirring occasionally, until the sauce is thickened (~15 minutes). Add the marsala (if using); stir. Simmer for 2 additional minutes.
  • While the sauce simmers, toss the green beans with the cornstarch. Add to a 9x13 baking dish.
  • Taste the sauce and adjust seasoning as needed with S&P. (NOTE: you want the sauce to be on the salty side, since the green beans are not salted.) Pour the sauce over the beans and push the beans down so that they’re completely covered with sauce. Press plastic wrap over the surface of the casserole, making sure there are no air pockets. Cover the baking dish tightly with foil. Refrigerate or freeze (see below).
  • You can do all of the above and freeze the dish; thaw three days before serving. Otherwise, make the dish up to two days before serving and keep in the refrigerator.


  • Make the topping by mixing the melted butter with the panko, fried onions, and S&P. Unwrap the dish, discard plastic wrap. Sprinkle the topping evenly over the casserole; re-cover with foil. Allow the casserole to sit at room temperature for about an hour before it goes in the oven. Bake the casserole at 350° for 20 minutes, covered. Remove foil; bake an additional 10 minutes or until topping is golden-brown.


*If you'd like, you can chop up an additional cup of the fried onions and mix them in with the beans and sauce to kick the flavor up even more. However, I don't recommend this strategy if you're planning to freeze the casserole.