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French Onion Grilled Cheese

A gourmet twist on the classic sandwich, featuring deeply caramelized onions, melted Gruyère and Mozzarella, and toasted sourdough bread.
Print Recipe
Prep Time 10 minutes
Cook Time 40 minutes
Total Time 50 minutes
Servings: 2 sandwiches
Course: Dinner, Lunch
Cuisine: American, French
Calories: 680
Ingredients Equipment Method Notes

Ingredients
  

Caramelized Onions
  • 2 large yellow onions thinly sliced
  • 2 tbsp unsalted butter
  • 1 tbsp olive oil
  • 1 tsp fresh thyme leaves only
  • 0.25 cup dry white wine or beef broth
Sandwich Build
  • 4 slices sourdough bread thick cut
  • 1 cup Gruyère cheese shredded
  • 0.5 cup Mozzarella cheese shredded
  • 3 tbsp butter softened, for spreading

Equipment

  • Large skillet or pan
  • Spatula
  • Knife
  • Cutting board

Method
 

  1. Heat 2 tbsp butter and olive oil in a large skillet over medium heat. Add onions and cook for 5 minutes.
  2. Reduce heat to medium-low. Cook onions for 30-35 minutes, stirring occasionally, until deep golden brown and jammy.
  3. Stir in thyme and white wine (or broth). Scrape up brown bits from the pan and cook until liquid evaporates. Remove onions from heat.
  4. Butter one side of each slice of sourdough bread.
  5. Mix Gruyère and Mozzarella cheeses together. Place bread butter-side down on a board.
  6. Layer half the cheese, then all the onions, then the remaining cheese onto two slices of bread. Top with remaining bread, butter-side up.
  7. Wipe out the skillet and heat over medium-low. Place sandwiches in the pan.
  8. Grill for 4-5 minutes per side until bread is golden brown and cheese is fully melted.

Notes

Grate your own cheese for the best melt. Pre-shredded cheese contains anti-caking agents that prevent a smooth texture.