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Caramelized Onion Grilled Cheese

Close-up of a perfectly grilled caramelized onion grilled cheese sandwich, with melted Gruyere cheese oozing out.
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A gourmet grilled cheese sandwich with sweet caramelized onions, melty Gruyere cheese, and tangy sourdough bread. This sandwich is perfect for a quick lunch or a comforting weeknight dinner.

Ingredients

Scale
  • 2 tablespoons unsalted butter, divided
  • 1 large yellow onion, thinly sliced
  • 1/4 teaspoon salt
  • 1/4 teaspoon black pepper
  • 4 slices sourdough bread
  • 2 tablespoons mayonnaise
  • 4 ounces Gruyere cheese, grated or thinly sliced
  • Optional: 1 tablespoon blackberry jam

Instructions

  1. Melt 1 tablespoon of butter in a skillet over medium-low heat. Add the sliced onion and cook, stirring occasionally, until softened, about 5-7 minutes.
  2. Add the salt and pepper. Continue cooking, stirring more frequently as the onions begin to brown, until they are deeply caramelized and sweet, about 20-30 minutes. If the onions start to stick, add a tablespoon of water. Remove onions from skillet and set aside.
  3. Spread mayonnaise on one side of each slice of sourdough bread.
  4. Place two slices of bread, mayonnaise-side down, in the skillet over medium heat.
  5. Top each slice with half of the Gruyere cheese, then half of the caramelized onions. If using, spread jam on the un-mayonnaised side of the remaining two bread slices and place them jam-side down on top of the onions.
  6. Cook for 3-5 minutes, until the bread is golden brown and the cheese is starting to melt.
  7. Carefully flip the sandwiches and cook for another 3-5 minutes, until the second side is golden brown and the cheese is fully melted and gooey.
  8. Slice in half and serve immediately.

Notes

  • For extra flavor, you can add a splash of balsamic vinegar to the onions during the last 5 minutes of caramelizing.
  • If you don’t have Gruyere, Swiss or sharp cheddar cheese also work well.
  • This sandwich is delicious served with a side of tomato soup.

Nutrition

Find it online: https://gourmetgaze.com/caramelized-onion-grilled-cheese/