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–+ servings
Close-up of a perfectly grilled cheese sandwich with melted cheese oozing out, featuring caramelized onions.

Caramelized Onion Grilled Cheese

This recipe elevates the classic grilled cheese with sweet caramelized onions and a blend of melty cheeses. It's perfect for a quick and satisfying meal.
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Prep Time 15 minutes
Cook Time 20 minutes
Caramelizing Onions 1 minute
Total Time 36 minutes
Servings: 4 sandwiches
Course: Dinner, Lunch
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

For the Caramelized Onions
  • 1.5 Tbsp butter
  • 1 Tbsp olive oil
  • 2 cups yellow onions diced
  • 1 tsp fresh thyme minced
  • 1 tsp fresh rosemary minced
  • 1 tsp brown sugar
  • to taste salt
  • to taste pepper
For the Grilled Cheese
  • 8 slices bread thick cut artisan bread recommended
  • as needed mayonnaise
  • 12 oz Gruyere cheese sliced thinly or grated, at room temperature
  • 6 oz white cheddar cheese sliced thinly or grated, at room temperature
  • 4 slices Muenster cheese at room temperature
  • 1.5 Tbsp butter divided
  • 1 tsp fresh rosemary minced

Equipment

  • Skillet
  • Spatula
  • Plate

Method
 

  1. Heat 1 1/2 Tbsp butter and olive oil in a skillet over medium-low heat. Add diced onions, salt, pepper, fresh thyme, and 1 tsp of fresh rosemary. Sauté, stirring often, until onions are soft and starting to brown, about 10 minutes.
  2. Stir brown sugar into the onions and cook for another minute.
  3. Transfer the caramelized onions to a plate.
  4. Spread a thin layer of mayonnaise on one side of two pieces of bread.
  5. To the same skillet, add the remaining butter and minced rosemary. Heat over medium heat, swirling to coat the bottom of the skillet with the melted butter.
  6. Add both pieces of bread to the skillet, mayonnaise side down. Cook until the bread is golden brown and crunchy, about 2-3 minutes.
  7. As soon as you add the bread to the skillet, add cheese to the top of each piece. Once the cheese begins to melt slightly, sprinkle a couple tablespoons of the caramelized onions over the top of one of the pieces of bread.
  8. When the bread is golden brown, sandwich the two pieces of bread together. Cook on low heat until the cheese is fully melted.
  9. Transfer the sandwich to a plate. Repeat with the remaining slices of bread and ingredients.
  10. Slice and enjoy your grilled cheese sandwiches.

Notes

For best results, ensure your cheeses are at room temperature before assembling the sandwiches. This helps them melt more evenly.

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