Description
A classic and creamy green bean casserole featuring tender blanched green beans, a rich mushroom sauce infused with tamari, garlic, and thyme, topped with crispy French fried onions and Parmesan cheese.
Ingredients
Scale
Vegetables and Toppings
- 1½ pounds green beans, trimmed and halved
- 16 ounces cremini mushrooms, sliced
- 4 garlic cloves, minced
- 2 tablespoons fresh thyme leaves
- 1½ cups French fried onions, or homemade Crispy Baked Onions
- ½ cup grated Parmesan cheese, plus more for sprinkling
Sauce and Seasonings
- 2 tablespoons extra-virgin olive oil
- 2 tablespoons tamari
- ¼ cup all-purpose flour
- 3 cups milk, any kind
- 1½ teaspoons Dijon mustard
- ¼ teaspoon freshly ground black pepper
Instructions
- Preheat and Prepare Baking Dish: Preheat the oven to 400°F. Lightly grease a 9×13-inch baking dish to prepare for assembling the casserole.
- Blanch Green Beans: Bring a large pot of salted water to a boil and have a large bowl of ice water ready. Drop the green beans into boiling water and blanch for 4 minutes. Drain and immediately immerse in the ice water to stop cooking. Drain again and dry with a towel.
- Cook Mushrooms and Make Sauce: Heat olive oil in a large skillet over medium heat. Add sliced mushrooms and cook until soft, about 8 to 10 minutes. Stir in tamari, minced garlic, and fresh thyme leaves. Sprinkle the flour over the mushroom mixture and stir well to coat. Slowly add milk and Dijon mustard while stirring to combine. Simmer, whisking often, until the sauce thickens, about 15 to 20 minutes. Stir in grated Parmesan cheese and ground black pepper.
- Assemble Casserole: Spread one-third of the mushroom sauce in the prepared baking dish. Layer the blanched green beans evenly over the sauce, then top with the remaining mushroom sauce. Sprinkle the French fried onions evenly on top.
- Bake: Cover the dish and bake for 10 minutes at 400°F. Then uncover and bake for an additional 10 minutes. If the onions begin to brown too quickly, cover the dish for the remainder of the baking time.
- Garnish and Serve: Optionally sprinkle extra Parmesan cheese on top before serving. Serve the casserole hot and enjoy.
Notes
- For homemade Crispy Baked Onions: Preheat oven to 450°F. Thinly slice 2 medium yellow onions and toss with 4 teaspoons olive oil, ½ cup all-purpose flour, 2 tablespoons panko bread crumbs, and ½ teaspoon sea salt. Spread evenly on parchment-lined baking sheets and bake for 25 to 35 minutes, tossing every 10 minutes, until lightly browned and crispy.
- To make the casserole vegan, omit the Parmesan cheese and add extra salt to the mushroom sauce for flavor balance.
- If avoiding gluten, use gluten-free tamari and substitute the all-purpose flour with a gluten-free alternative.
- Blanching the green beans helps retain their vibrant color and crisp texture in the casserole.
Nutrition
- Serving Size: 1 cup
- Calories: 220 kcal
- Sugar: 4 g
- Sodium: 400 mg
- Fat: 10 g
- Saturated Fat: 3 g
- Unsaturated Fat: 6 g
- Trans Fat: 0 g
- Carbohydrates: 22 g
- Fiber: 4 g
- Protein: 8 g
- Cholesterol: 10 mg
