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–+ servings
A perfectly toasted Grilled Cheese Recipes Meal Prep sandwich cut in half, showing a dramatic cheese pull and caramelized onions.

Caramelized Onion and Gruyere Grilled Cheese

This recipe shows you how to make a flavorful grilled cheese sandwich with caramelized onions, perfect for a quick meal or meal prep. You will use a mix of Gruyere, white cheddar, and Muenster cheese for a great melt.
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Prep Time 10 minutes
Cook Time 15 minutes
Total Time 25 minutes
Servings: 4 sandwiches
Course: Dinner, Lunch
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

For the Caramelized Onions
  • 2 yellow onions diced
  • 1 tsp fresh thyme minced
  • 2 tsp fresh rosemary minced, divided
  • 1 tsp brown sugar
  • to taste Salt and pepper
  • 1.5 Tbsp butter
  • 1 Tbsp olive oil
For the Sandwich
  • 8 slices good quality bread thick cut Artisan bread recommended
  • Mayonnaise for spreading
  • 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 thin Muenster cheese at room temperature
  • 1.5 Tbsp butter remaining
  • 1 tsp fresh rosemary remaining

Equipment

  • Skillet

Method
 

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

Notes

This sandwich works well for meal prep. You can assemble the sandwiches (bread, cheese, onions) and keep them refrigerated for up to 24 hours before grilling. If you need gluten-free options, experiment with your favorite gluten-free bread brands.

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