Ingredients
For the Casserole:
- nonstick spray (or unsalted butter, for casserole dish)
- 1½ pounds green beans (stems trimmed and discarded)
- 6 tablespoons unsalted butter (for blanching green beans)
- 1 cup diced yellow onion
- kosher salt
- 3/4 cup finely chopped mushrooms
- 2 cloves garlic (minced)
- 1/4 cup unbleached all-purpose flour
- 2 tablespoons dry white wine (Chardonnay or Sauvignon Blanc)
- 2 cups half & half
- 1/4 cup parmesan cheese (freshly grated)
- 1 teaspoon kosher salt (more or less to taste)
- 1/2 teaspoon freshly ground black pepper (more or less to taste)
- 1/8 teaspoon nutmeg (grated fresh or ground)
For the Fried Shallot Topping:
- 3 tablespoons unsalted butter
- 3 large shallots (thinly sliced)
- pinch of kosher salt
Instructions
- Preheat and Prepare Dish: Preheat your oven to 350°F (180°C). Grease a 2 to 3-quart oven-safe casserole dish using olive oil spray or unsalted butter to prevent sticking.
- Blanch the Green Beans: Trim the stems and discard. Bring a deep skillet of water to a boil with a handful of sea salt. Add green beans, submerge, and return to boiling. Cook for 6 minutes. Remove beans with tongs and immediately transfer to a bowl of ice water to stop cooking and preserve bright green color. Drain, pat dry, and cut the beans into thirds or halves if small.
- Sauté Onions and Mushrooms: In a 10-inch skillet, melt 6 tablespoons butter over medium heat. Add diced onion and cook for about 8 minutes until soft and translucent. Add chopped mushrooms and cook for 4 more minutes. Add minced garlic and cook for 1 minute until fragrant.
- Make the Sauce: Sprinkle flour over the vegetables and stir, cooking for 2 minutes to remove raw flour taste. While stirring, slowly pour in 2 tablespoons dry white wine and 2 cups half & half. Bring the mixture to a simmer and cook until thickened to a creamy sauce consistency. Remove from heat and stir in parmesan cheese, kosher salt, black pepper, and nutmeg. Adjust seasoning to taste.
- Combine Beans and Sauce: Add the blanched, cut green beans to the creamy sauce and toss to coat evenly. Transfer this mixture to the prepared casserole dish and spread evenly. Cover with aluminum foil.
- Bake the Casserole: Place the covered dish in the preheated oven on the middle rack and bake for 20 minutes while you prepare the shallot topping.
- Prepare Fried Shallot Topping: Melt 3 tablespoons unsalted butter in an 8-inch skillet over medium to medium-low heat. Add thinly sliced shallots with a pinch of kosher salt. Toss often and cook for about 10 minutes until shallots are slightly crispy but not browned, as they will crisp more in the oven.
- Top and Finish Baking: Carefully remove the casserole from the oven, discard the foil, and sprinkle the fried shallots evenly over the top. Return the casserole to the oven and bake uncovered for an additional 15 to 20 minutes until the shallots are deeply golden and the casserole is bubbling with lightly browned edges.
- Rest and Serve: Allow the casserole to rest for 10 minutes before serving to let it set and enhance flavors.
Notes
- Blanching the green beans ensures they retain their vibrant green color and crisp-tender texture.
- Use fresh parmesan for best flavor and texture in the sauce.
- Watch the shallots carefully while frying to avoid burning; they will continue to crisp in the oven.
- The casserole can be assembled ahead and refrigerated before baking; add extra baking time if chilled.
- For a richer flavor, substitute half & half with heavy cream, but expect higher calories.
- Adjust seasoning after combining sauce and green beans as taste may vary.
- Prep Time: 25 minutes
- Cook Time: 45 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: American
