Go Back
The heart of a great french onion grilled cheese recipe lies in its key ingredients. First, you need sweet onions. They help create that rich, sweet flavor when cooked. I recommend using two large sweet onions for the best taste.

French Onion Grilled Cheese Sandwich

Indulge in the comforting flavors of my Savory French Onion Grilled Cheese Sandwich! This recipe combines sweet caramelized onions with a delicious blend of Gruyère and sharp cheddar cheeses, all tucked between crispy, buttery bread. Perfect for a cozy meal, I’ll guide you through each easy step and share tips for variations. Click through to explore this mouthwatering recipe and impress your taste buds today!
Print Recipe Pin Recipe

Ingredients
  

2 large sweet onions, thinly sliced

2 tablespoons unsalted butter

1 tablespoon olive oil

1 teaspoon sugar

1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried thyme)

4 slices of crusty bread (like sourdough or country bread)

4 slices of Gruyère cheese

4 slices of sharp cheddar cheese

Salt and pepper to taste

1 tablespoon balsamic vinegar

Optional: Fresh parsley, chopped (for garnish)

Instructions
 

In a large skillet, melt the butter and olive oil over medium heat.

    Add the sliced onions and sprinkle with sugar. This will help the onions caramelize.

      Cook the onions for about 20-25 minutes, stirring occasionally, until they are golden brown and softened.

        Stir in the thyme, balsamic vinegar, salt, and pepper; cook for an additional 2-3 minutes until well combined. Remove from heat and set aside.

          Heat a separate skillet or griddle over medium-low heat.

            Butter one side of each slice of bread.

              Place two slices of bread, buttered side down, on the skillet.

                Layer on one slice of Gruyère and one slice of cheddar cheese on each piece of bread.

                  Spoon a generous amount of the caramelized onions over the cheeses.

                    Top with another slice of Gruyère and cheddar cheese, then place the second slice of bread on top, buttered side up.

                      Cook for 3-4 minutes on each side, or until the bread is golden brown and the cheese is melted.

                        Remove from the skillet and let cool for a minute before slicing in half.

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

                            - Presentation Tips: Serve the sandwich on a wooden board, cut diagonally, and garnish with chopped fresh parsley for a touch of color. Pair with a side of crispy potato chips or a small green salad for a complete meal.