Prep Time: 15 minutes | Cooking Time: 25 minutes | Total Time: 40 minutes
Kcal: 520 kcal | Servings: 4 servings
Ingredients:
- 1 pound ground beef
- 2 large onions, thinly sliced
- 2 tablespoons butter
- 1 tablespoon olive oil
- 1 teaspoon sugar
- 2 teaspoons Worcestershire sauce
- 4 slices Swiss cheese
- 4 burger buns
- Salt and pepper to taste
- Fresh thyme, for garnish (optional)
