Caramelized Onion & Gruyère Grilled Cheese (Printable)

Gourmet grilled cheese with sweet caramelized onions, nutty Gruyère, and crispy country bread. A French-inspired comfort classic.

# What you'll need:

→ 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

→ Sandwiches

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

# Method:

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

# Expert Advice:

01 -
  • The slow cooked onions develop a natural sweetness that balances perfectly with the nutty sharpness of Gruyère
  • This is comfort food elevated enough for dinner guests but simple enough for a lonely Tuesday night
02 -
  • Caramelizing onions takes longer than you expect, and rushing them over high heat just makes them bitter and burned
  • Low and slow is the only way to get that deep jammy texture that makes these sandwiches special
03 -
  • Cast iron skillets give the most even browning and that satisfying crunch
  • A lid on the pan for the first minute helps melt the cheese before the bread burns
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