Ingredients
Scale
- 2 large yellow onions, thinly sliced
- 2 tablespoons butter (plus more for grilling)
- 1 teaspoon fresh thyme
- 2 tablespoons beef broth (optional)
- 4 slices sturdy bread (like sourdough)
- 1 cup shredded Gruyère
- 1/2 cup shredded mozzarella
- Salt and pepper
Instructions
- Caramelize onions with butter and thyme over medium-low heat for 30–40 minutes.
- Add beef broth and cook until it evaporates.
- Butter bread slices. Layer cheese, onions, and more cheese.
- Grill sandwiches 3–4 minutes per side until golden and melty.
- Serve hot and enjoy!
Nutrition
- Calories: 550
- Fat: 35g
- Carbohydrates: 38g
- Fiber: 3g
- Protein: 20g