Name: French Onion Grilled Cheese Recipe
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Cuisine: French-Inspired
Ingredients: 8 slices of sourdough or thick sandwich bread; 2 cups shredded Gruyère cheese (or Swiss); Optional: 4 slices provolone cheese; 2 tablespoons butter (plus more for spreading); 2 tablespoons olive oil; 2 large yellow onions, thinly sliced; 1/2 teaspoon salt; 1/4 teaspoon black pepper; 1/2 teaspoon sugar; 1 tablespoon balsamic vinegar; 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried)

Description

This French Onion Grilled Cheese combines deeply caramelized onions with rich Gruyère cheese layered between buttery sourdough bread, creating a savory and comforting sandwich perfect for a cozy meal or lunch.

Ingredients

Scale

Bread and Cheese

8 slices of sourdough or thick sandwich bread
2 cups shredded Gruyère cheese (or Swiss)
Optional: 4 slices provolone cheese

Caramelized Onions

2 tablespoons butter (plus more for spreading)
2 tablespoons olive oil
2 large yellow onions, thinly sliced
1/2 teaspoon salt
1/4 teaspoon black pepper
1/2 teaspoon sugar
1 tablespoon balsamic vinegar
1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried)

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Instructions

Caramelize the Onions: In a large skillet, heat olive oil and 2 tablespoons of butter over medium heat. Add the thinly sliced onions along with salt, pepper, and sugar. Cook for 25–30 minutes, stirring occasionally, until the onions become deeply golden and caramelized. Stir in the balsamic vinegar and thyme, cook for an additional minute, then remove the skillet from heat.
Prepare the Bread and Cheese: Butter one side of each bread slice evenly. On the unbuttered side of four slices, layer shredded Gruyère cheese, then spoon a generous portion of the caramelized onions on top. Add optional provolone cheese slices if using. Top with the remaining bread slices, ensuring the buttered side is facing outward.
Grill the Sandwiches: Heat a clean skillet or griddle over medium heat. Place the sandwiches in the skillet and grill for 3 to 4 minutes per side, pressing gently with a spatula, until the bread is golden brown and the cheese is fully melted.
Serve: Let the sandwiches rest for 1 minute before slicing. Serve warm for the best flavor and texture.

Notes

For extra richness, use a mix of cheeses such as fontina or white cheddar along with Gruyère.
Caramelized onions can be made ahead of time and stored in the refrigerator for up to 3 days.
This sandwich pairs beautifully with a cup of tomato soup or a fresh green salad for a complete meal.