6 cups green beans, trimmed and cut into 1-inch pieces
4-1/2 teaspoons extra-virgin olive oil, divided
2 tablespoons unsalted butter
1 cup mushrooms, finely-chopped
3 shallots, minced
2 teaspoons fresh thyme, finely-chopped
1/2 teaspoon salt
1/4 teaspoon ground pepper
1/2 cup dry white wine
1/3 cup all-purpose flour
1 cup reduced-sodium broth (chicken or vegetable)
1 cup low-fat milk
2 cups sharp cheddar cheese, shredded and divided
1/2 cup dry breadcrumbs
1/2 teaspoon paprika
1/4 teaspoon onion powder
Non-stick cooking spray
Preheat oven to 425 F. Coat the inside of a a 2-1/2 quart baking dish with non-stick spray.
Steam green beans on the stove for about 4 minutes until they are crisp tender. Plunge the beans into cold water to stop the cooking process and to preserve color and texture.
Heat 3 teaspoons of oil and the unsalted butter in a large skillet over medium-high heat. Stir until melted together. Add the shallots and cook for 2 to 3 minutes until very lightly browned.
Add the chopped mushrooms, thyme, salt and pepper to the pan, stirring as needed for 3 to 4 minutes or until most of the liquid is gone.
Add wine and continue to cook, stirring as needed for 3 to 4 minutes until most of the liquid is again gone.
Sprinkle flour over the mushroom mixture and stir to coat. Add broth and milk and bring to a simmer stirring often until the sauce is thickened, about 5 minutes.
Remove from heat but leave in the pan. Stir in 1-1/2 cups of grated cheddar cheese until fully combined. When mixed, add the green beans and stir to combine.
Transfer the mixture to your prepared casserole dish. Top with the remaining cheddar cheese.
In a small bowl, stir together 1-1/2 teaspoons olive oil and the breadcrumbs. After oil is integrated, add the paprika and onion powder and stir until combined. Sprinkle the crumb mixture evenly over the top of the casserole.
Place the casserole dish in the oven, and bake 22-25 minutes, or until bubbling and starting to brown. Before serving, allow the casserole to cool for 15 to 20 minutes.