French Onion Grilled Cheese Sandwich

Indulge in the ultimate comfort food with this French Onion Grilled Cheese Sandwich recipe! Packed with gooey cheese, caramelized onions, and a touch of Dijon, this easy and tasty meal is perfect for impressing guests or enjoying a cozy night in. Discover how to master the art of caramelization for sweet, rich flavors, and explore delicious variations to make it your own. Click to reveal the full recipe and elevate your sandwich game!

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Ingredients

2 large yellow onions, thinly sliced

2 tablespoons unsalted butter

1 tablespoon olive oil

1 teaspoon sugar

Salt and pepper to taste

4 slices of sourdough bread

4 slices of Gruyère cheese

1 slice of aged cheddar cheese

1 tablespoon Dijon mustard

Fresh thyme leaves for garnish

Instructions

In a large skillet, melt the butter and olive oil over medium heat. Add the sliced onions and a pinch of salt.

Cook the onions slowly, stirring occasionally, until they become soft and caramelized, about 20-25 minutes. Add the sugar halfway through to help with caramelization.

Once the onions are golden brown and caramelized, season with salt and pepper to taste. Remove the skillet from heat and set aside.

Heat a separate non-stick skillet over medium heat. Spread Dijon mustard on one side of each slice of sourdough bread.

Place 2 slices of bread, mustard-side up, in the skillet. Layer with 2 slices of Gruyère cheese, half of the caramelized onions, and a slice of aged cheddar cheese. Top with the remaining Gruyère and then the other slices of bread, mustard-side down.

Grill the sandwiches for about 3-4 minutes on each side, pressing down lightly, until the bread is golden brown and the cheese is melted.

Repeat the grilling process with the second sandwich.

Once done, let the sandwiches rest for a minute, then slice diagonally and garnish with fresh thyme leaves.

Prep Time: 10 minutes | Total Time: 40 minutes | Servings: 2 sandwiches

- Presentation Tips: Serve on a wooden cutting board with a side of fresh arugula salad sprinkled with a light vinaigrette. For an added touch, drizzle a little balsamic glaze over the sandwich for extra flavor.