Golden, buttery bread hugs layers of melted cheese and deeply caramelized onions in this comforting twist on a classic. Slow-cooked onions bring a rich, sweet-savory depth that pairs perfectly with gooey, stretchy cheese, creating bold French onion flavor in every bite. Crisp edges give way to a soft, melty center, making it indulgent yet familiar. It’s a cozy choice for lunch, dinner, or an elevated snack. Enjoy it on its own or with a warm bowl of soup for the ultimate comfort meal.
Ingredients
- 5 tablespoons butter, softened, divided
- 1 tablespoon olive oil
- 2 medium onions, thinly sliced
- 1/2 teaspoon dried thyme
- 1/2 teaspoon dried rosemary, crushed
- 1 bay leaf
- 1 teaspoon packed brown sugar
- 1/2 teaspoon pepper
- 3 tablespoons grated Parmesan cheese
- 1/4 cup water
- 1 ounce au jus gravy mix
- 8 slices sourdough bread
- 8 slices Swiss cheese
- 1 cup shredded Gruyere cheese
Instructions
- In a large skillet, heat 1 tablespoon butter and olive oil over medium heat. Add onion, thyme, rosemary, bay leaf, brown sugar and pepper. Cover; cook over medium-low heat for 15-20 minutes, stirring occasionally, until onions are soft and lightly browned.
- Meanwhile, in a small bowl, combine Parmesan cheese and remaining 4 tablespoons softened butter; set aside.
- Remove the lid from the skillet; increase heat to medium. Add water and aus jus mix; simmer until reduced, 2-3 minutes. Remove from heat; discard bay leaf.
- Preheat a large nonstick skillet or griddle over medium heat.
- Top each slice of bread with two slices Swiss cheese and 1/4 of the onion mixture. Sprinkle each with 1/4 cup Gruyere; top with another slice of bread. Spread both sides of each sandwich with Parmesan butter.
- Place sandwiches on the preheated griddle. Cook until golden brown and cheese is melted, 3-4 minutes per side. Remove to a cutting board; cut each sandwich in half. Serve immediately.
