6 tablespoons butter
48 ounces white button mushrooms sliced
4.5 cups chicken broth
1.5 teaspoon garlic powder
1.5 teaspoon onion powder
3 cup milk
1.5 cup all-purpose flour
Salt and freshly ground black pepper
For the casserole:
3 pound ground beef
2.25 cup onion chopped
1.5 cup celery chopped
3 cup frozen cut green beans thawed
Salt and freshly ground black pepper
3 (16 ounce) package frozen tater tots

6 tablespoons butter 48 ounces white button mushrooms sliced 4 5 cups chicken broth 1 5 teaspoon garlic powder 1 5 teaspoon onion powder 3 cup milk 1 5 cup all-purpose flour 3 pound ground beef 2 25 cup onion chopped 1 5 cup celery chopped 3 cup frozen cut green beans thawed 3 (16 ounce) package frozen tater tots

In a large saucepan over medium-high heat, melt butter until foaming. Add mushrooms and cook until they have released most of their liquid, about 5 to 7 minutes.
Stir in chicken broth, garlic powder, and onion powder. Bring to simmer. Meanwhile, in a small bowl whisk together milk and flour.
Stir in milk mixture and cook until soup has thickened, about 1 minute. Season to taste with salt and pepper.
To make the casserole:
Preheat oven to 375 degrees. In a large saucepan, brown the ground beef, celery, and onions until the beef is cooked thoroughly. Drain.
Stir in mushroom sauce and green beans. Season to taste with salt and pepper. Carefully spoon the mixture into a 2-quart casserole pan. Top the mixture with the frozen potato tots.
Bake uncovered until the casserole is bubbly and the tots are golden brown, about 40 to 50 minutes