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Creamy Green Bean Casserole with Mushrooms and Crispy Onions Recipe

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4.3 from 59 reviews

This Green Bean Casserole is a delicious and upgraded take on a classic comfort dish, perfect for dinner or holiday gatherings. Featuring fresh green beans blanched to crisp-tender perfection, sautéed cremini mushrooms, and a creamy, flavorful sauce made with Parmesan and Dijon mustard, all topped with crispy French fried onions for a delightful crunch. The casserole is baked until bubbly and golden, making it a hearty and satisfying vegetable side dish.

  • Total Time: 1 hour 20 minutes
  • Yield: 8 servings

Ingredients

Vegetables

  • 1½ pounds green beans (trimmed and halved)
  • 16 ounces cremini mushrooms (sliced)
  • 4 garlic cloves (minced)
  • 2 tablespoons fresh thyme leaves

Sauce and Seasoning

  • 2 tablespoons extra-virgin olive oil
  • 2 tablespoons tamari
  • ¼ cup all-purpose flour
  • 3 cups milk (any kind)
  • 1½ teaspoons Dijon mustard
  • ½ cup grated Parmesan cheese (plus more for sprinkling)
  • ¼ teaspoon freshly ground black pepper

Topping

  • 1½ cups french fried onions (or homemade Crispy Baked Onions, see recipe notes)

Instructions

  1. Preheat Oven and Prepare Dish: Preheat your oven to 400°F (204°C). Lightly grease a 9×13-inch baking dish to prevent sticking and set aside.
  2. Blanch Green Beans: Bring a large pot of salted water to a boil. Prepare a large bowl of ice water nearby. Add the trimmed and halved green beans to the boiling water and blanch for 4 minutes until crisp-tender. Immediately transfer green beans to the ice water to halt cooking. Drain and dry thoroughly on a clean towel.
  3. Sauté Mushrooms and Aromatics: Heat extra-virgin olive oil in a large skillet over medium heat. Add sliced cremini mushrooms and cook until soft, approximately 8 to 10 minutes. Stir in tamari, minced garlic, and fresh thyme leaves, cooking briefly to blend flavors.
  4. Make the Creamy Sauce: Sprinkle the all-purpose flour over the mushrooms and stir well to combine. Slowly add milk and Dijon mustard while stirring. Simmer the mixture gently, whisking often, until it thickens, about 15 to 20 minutes. Remove from heat and stir in grated Parmesan cheese and freshly ground black pepper for a rich, savory flavor.
  5. Assemble the Casserole: Spread one-third of the mushroom sauce evenly on the bottom of the prepared baking dish. Layer the drained green beans evenly over the sauce. Pour the remaining sauce over the green beans, spreading it out evenly. Top the casserole with French fried onions, and sprinkle additional Parmesan cheese if desired.
  6. Bake the Casserole: Cover the dish with foil and bake in the preheated oven for 10 minutes. Then remove the foil and bake uncovered for an additional 10 minutes to allow the onions to crisp up and the casserole to bubble. If the onions brown too quickly, cover the dish loosely to prevent burning while baking the remainder of the time.

Notes

  • To make homemade crispy baked onions as a substitute for French fried onions, thinly slice onions, toss with a little flour and seasonings, then bake until golden and crisp.
  • You can use any kind of milk for the sauce, including dairy-free alternatives like almond or oat milk.
  • Tamari is used here instead of soy sauce for a gluten-free option; regular soy sauce can be substituted if preferred.
  • Be sure to dry the blanched green beans thoroughly to prevent the casserole from becoming watery.
  • This casserole can be prepared ahead and baked just before serving for convenience.
  • Author: Olivia
  • Prep Time: 20 minutes
  • Cook Time: 1 hour
  • Category: Side Dish
  • Method: Baking
  • Cuisine: American
  • Diet: Gluten Free

Find it online: https://yourdailycook.com/creamy-green-bean-casserole-with-mushrooms-and-crispy-onions-recipe/