This pasta dish tastes like French Onion Soup! Onions are sautéed in a skillet with sugar, Worcestershire sauce, thyme, salt and pepper. Beef broth is added in next and the onions simmer until caramelized. Cooked gnocchi is placed in a casserole dish. A white sauce is made with flour, butter and milk. The onions are placed over the gnocchi, then the white sauce is poured on top and mozzarella cheese is sprinkled on last. This dish is baked until the cheese is golden brown. Caramelizing onions gives this dish the classic French Onion Soup flavor.