Mushroom Burger Casserole

Name: Mushroom Burger Casserole
Cook time: 45 min
Total time: 45 min
Cuisine: American
Ingredients: 1 pound lean ground beef; 1 (16 oz.) package potato dumplings or gnocchi; 8 oz. baby portobello mushrooms, sliced; 1 yellow onion, finely chopped; 4 cloves garlic, minced; 2 teaspoons Italian seasoning; 2 tablespoons unsalted butter; 2 tablespoons extra-virgin olive oil; 2 tablespoons Worcestershire sauce; 1 (15 oz.) can cream of mushroom soup; 1 cup heavy whipping cream; 2 cups Swiss cheese, grated; kosher salt and freshly ground pepper, to taste