Caramelized Onion Gruyère Grilled Cheese (Printable)

Sweet caramelized onions and nutty Gruyère melted between crispy golden country bread for gourmet comfort.

# Ingredient List:

→ Caramelized Onions

01 - 2 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1 tablespoon olive oil
04 - 1/2 teaspoon salt
05 - 1/4 teaspoon freshly ground black pepper
06 - 1 teaspoon fresh thyme leaves
07 - 1 teaspoon balsamic vinegar

→ Sandwich Assembly

08 - 4 slices rustic country bread
09 - 4 ounces Gruyère cheese, grated
10 - 1 tablespoon unsalted butter, softened

# How-To Steps:

01 - Melt butter with olive oil in a large skillet over medium-low heat. Add sliced onions, salt, and pepper. Cook stirring occasionally until deeply golden and caramelized, about 25–30 minutes. Stir in thyme and balsamic vinegar, cook 1 minute longer. Remove from heat.
02 - Lay out bread slices. Spread caramelized onions evenly on two slices. Top each with half the grated Gruyère. Close sandwiches with remaining bread slices.
03 - Spread softened butter evenly on the outside of each sandwich.
04 - Heat a non-stick skillet or griddle over medium heat. Place sandwiches in pan and cook until golden brown with melted cheese, about 3–4 minutes per side. Press gently with spatula for even toasting.
05 - Slice sandwiches in half and serve immediately while hot.

# Expert Hints:

01 -
  • The combination of sweet onions and nutty Gruyère creates that perfect melty pull-apart moment that makes grilled cheese so satisfying
  • This recipe elevates a childhood favorite into something fancy enough for dinner guests but simple enough for a Tuesday night
02 -
  • Patience with the onions is absolutely non-negotiable, rush them and you'll miss out on that deep, sweet, complex flavor that makes this sandwich special
  • Low and slow heat for the onions prevents burning and encourages even browning
  • Letting the assembled sandwiches sit for a minute before grilling helps the bread absorb some onion moisture
03 -
  • Grating your own cheese makes a huge difference compared to pre-shredded, which has anti-caking agents that prevent smooth melting
  • Use a combination of butter and mayonnaise on the outside bread for an extra crispy, golden crust that won't burn as easily
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