Ground Beef Stroganoff Casserole

Name: Ground Beef Stroganoff Casserole
Cook time: 40 min
Total time: 40 min
Cuisine: European
Ingredients: 8 oz dry egg noodles; 1 lb lean ground beef; 4 tablespoons (1/2 stick) butter; 1 small white onion, diced; 2 cloves garlic, minced; 8 oz baby bella mushrooms, sliced; 2 tablespoons all-purpose flour; 2 1/2 cups beef broth; 3/4 cup sour cream; 1 tablespoon Dijon mustard; 2 cups mozzarella cheese, grated and divided