Make-Ahead Green Bean Casserole

Ingredients

• butter-flavored cooking spray
• 3 large shallots
• 1.25 pounds fresh green beans, trimmed and halved crosswise
• 2 tablespoons unsalted butter
• 1 (10 ounce) package button mushrooms, sliced
• 1/3 cup all-purpose flour, divided
• 1 cup half-and-half
• 1 cup chicken broth
• 1 teaspoon soy sauce
• salt and ground black pepper to taste
• 1 cup vegetable oil for frying, or as needed

Steps

1. Spray a 2 1/2-quart casserole dish with cooking spray. Mince shallots until you have 3 tablespoons; slice remaining shallots into 1/8-inch rounds. Set both aside.
2. Bring a large pot of lightly salted water to a boil. Add beans and cook until tender but still crisp, about 4 minutes. Drain, rinse, and pat dry; set aside.
3. Melt butter in a saucepan over medium heat. Add mushrooms and cook, stirring frequently, until browned, 5 to 7 minutes. Add minced shallots and cook until softened, 2 to 3 minutes. Stir in 3 tablespoons flour, then slowly add half-and-half, broth, and soy sauce. Bring to a boil while stirring.
4. Reduce heat to a simmer and stir until thickened, about 5 minutes. Stir in green beans and season with salt and pepper. Transfer to the prepared casserole dish, cover, and refrigerate 8 hours to overnight, or until ready to bake.
5. Preheat the oven to 350 degrees F (175 degrees C).
6. Remove casserole from the refrigerator and bake in the preheated oven until heated through and bubbly, about 30 minutes.
7. While the casserole is baking, dredge shallot rings in remaining flour until evenly coated.
8. Heat oil in a saucepan over medium heat. Lower shallots carefully into the hot oil, working in batches if necessary. Fry until golden brown, 1 to 2 minutes, then drain on paper towels.
9. Remove casserole from the oven and top with fried shallots.