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- 4 slices of sourdough bread - 1 medium onion, thinly sliced - 1 tablespoon butter - 1 teaspoon olive oil - 1 teaspoon sugar - 1/2 teaspoon salt - 1/4 teaspoon black pepper - 1 cup shredded Gruyère cheese - 1/2 cup shredded sharp cheddar cheese - 1 tablespoon fresh thyme leaves (or 1 teaspoon dried thyme) - 2 teaspoons balsamic vinegar - 1 tablespoon Dijon mustard (optional)

Gooey French Onion Grilled Cheese

Indulge in the ultimate comfort food with my Gooey French Onion Grilled Cheese recipe! This delicious twist on a classic features caramelized onions and a blend of rich cheeses for a mouthwatering experience. Perfectly toasted sourdough adds the finishing touch. Dive into each step to create this irresistible delight that will have you craving more.
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Ingredients
  

4 slices of sourdough bread

1 medium onion, thinly sliced

1 tablespoon butter

1 teaspoon olive oil

1 teaspoon sugar

1/2 teaspoon salt

1/4 teaspoon black pepper

1 cup shredded Gruyère cheese

1/2 cup shredded sharp cheddar cheese

1 tablespoon fresh thyme leaves (or 1 teaspoon dried thyme)

2 teaspoons balsamic vinegar

1 tablespoon Dijon mustard (optional)

Instructions
 

Caramelize the Onions: In a medium skillet, heat the butter and olive oil over medium heat. Add the thinly sliced onion, sugar, salt, and pepper. Sauté for 15-20 minutes, stirring frequently, until the onions are soft and deeply caramelized. If the onions start to stick to the pan, add a splash of water to deglaze. Stir in the balsamic vinegar and fresh thyme. Cook for an additional minute, and then remove from heat.

    Prepare the Bread: While the onions are caramelizing, spread a thin layer of Dijon mustard on one side of each slice of sourdough bread (if using).

      Assemble the Sandwich: On the uncoated side of two slices of bread, layer half of the Gruyère cheese, followed by half of the cheddar cheese, then a generous amount of caramelized onions, and top with the remaining cheese. Place the other two slices of bread on top, with the mustard side facing inward.

        Grill the Sandwiches: Heat a non-stick skillet or griddle over medium-low heat. Place the sandwiches in the skillet and cook for about 4-5 minutes on each side, or until the bread is golden brown and the cheese is melty and gooey. You may want to press down lightly on the sandwiches with a spatula to encourage even browning.

          Serve: Once both sides are perfectly golden and the cheese is thoroughly melted, remove the sandwiches from the skillet and let them sit for a minute before slicing.

            - Presentation Tips: Cut the sandwiches diagonally and serve on a rustic wooden board with a small bowl of warm French onion soup for dipping, and garnish with a sprig of thyme for a touch of elegance.

              Prep Time: 10 minutes | Total Time: 30 minutes | Servings: 2