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For a tasty French Onion Grilled Cheese Sandwich, you need several key ingredients. First, the onions. I prefer using large yellow onions. They caramelize beautifully and bring out a rich flavor.

French Onion Grilled Cheese Sandwich

Elevate your lunch with my delectable French Onion Grilled Cheese Sandwich guide! Discover the secrets to perfectly caramelized onions, the best cheese and bread combinations, and expert grilling tips for a crunchy, cheesy masterpiece. Whether you're a seasoned cook or a kitchen newbie, this recipe promises a warm, flavorful delight that's totally unforgettable. Click to explore the full recipe and transform your sandwich game today!
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Ingredients
  

2 large yellow onions, thinly sliced

2 tablespoons butter

1 teaspoon sugar

1 cup beef or vegetable broth

1 tablespoon balsamic vinegar

4 slices sourdough bread

1 cup grated Gruyère cheese

1 cup grated mozzarella cheese

Salt and pepper to taste

Olive oil for grilling

Instructions
 

In a large skillet over medium heat, melt the butter. Add the sliced onions and sugar, and cook for about 20 minutes, stirring occasionally until the onions are caramelized and golden brown.

    Pour in the broth and balsamic vinegar, stirring to combine. Let simmer for an additional 10 minutes until the liquid reduces slightly. Season with salt and pepper to taste, then remove from heat.

      Preheat a griddle or non-stick skillet over medium-low heat.

        Assemble the sandwiches by layering cheese on one slice of sourdough, followed by a generous amount of the caramelized onion mixture, topped with more cheese. Place another slice of bread on top to create the sandwich.

          Lightly brush the outer sides of the sandwich with olive oil. Place the sandwich on the preheated griddle and cook each side for about 4-5 minutes, or until the bread is golden brown and the cheese has melted.

            Repeat with remaining sandwiches, ensuring not to overcrowd the pan.

              Once cooked, remove from the skillet, allow to cool slightly, then cut in half to serve.

                Prep Time: 15 minutes | Total Time: 50 minutes | Servings: 2 sandwiches

                  - Presentation Tips: Serve the sandwiches on a wooden board with a side of homemade tomato soup for dipping, and garnish with fresh herbs for a pop of color.