Description
A gourmet twist on the classic grilled cheese sandwich featuring deeply caramelized onions, melted Gruyère and mozzarella cheeses, and aromatic thyme, all layered between crispy slices of sourdough or French bread. This French Onion Grilled Cheese is a comforting and flavorful vegetarian main course perfect for lunch or dinner.
Ingredients
Scale
Caramelized Onions
- 2 tablespoons unsalted butter
- 1 large yellow onion, thinly sliced
- 1/4 teaspoon salt
- 1/2 teaspoon sugar
- 1/4 teaspoon black pepper
- 1/2 teaspoon fresh thyme leaves (or 1/4 teaspoon dried thyme)
- 1 tablespoon dry white wine or beef broth (optional)
Sandwich
- 4 slices sourdough or French bread
- 1 cup shredded Gruyère cheese
- 1/2 cup shredded mozzarella cheese
- 1 tablespoon mayonnaise or softened butter (for bread)
Instructions
- Caramelize the Onions: Melt 1 tablespoon of butter in a skillet over medium heat. Add the thinly sliced onions, salt, sugar, black pepper, and thyme. Cook slowly, stirring frequently, until the onions turn deeply golden and caramelized, about 20–25 minutes.
- Deglaze the Pan: In the last few minutes of cooking the onions, add the white wine or beef broth if using. Stir well to deglaze the pan and incorporate all the flavorful browned bits. Remove the skillet from the heat and set aside.
- Prepare the Cheese Mixture: In a bowl, combine the shredded Gruyère and mozzarella cheeses and mix well.
- Prep the Bread: Spread mayonnaise or softened butter on one side of each slice of bread. This will help achieve a golden, crisp texture when grilled.
- Assemble and Grill the Sandwich: Heat a clean skillet over medium heat. Place two slices of bread, buttered side down, onto the skillet. Evenly distribute the cheese mixture on top of each slice, followed by half of the caramelized onions. Top with the remaining bread slices, buttered side up.
- Cook Until Golden: Cook the sandwiches until the bottom bread slices are golden brown and the cheese starts to melt, approximately 3–4 minutes. Carefully flip the sandwiches using a spatula and cook the other side until golden and the cheeses are fully melted.
- Serve: Remove from heat and let the sandwiches rest for 1–2 minutes to allow the cheese to set slightly. Slice and serve immediately, optionally alongside tomato soup or a fresh green salad.
Notes
- You can substitute Swiss cheese for Gruyère if preferred.
- For a stronger onion flavor, use red onions or add a splash of Worcestershire sauce during the onion cooking process.
- This sandwich pairs wonderfully with tomato soup or a crisp green salad for a complete meal.
