Caramelized Onion Gruyère Grilled Cheese (Printable)

Sweet caramelized onions and nutty Gruyère melted between crispy golden bread for a gourmet French-inspired twist on classic comfort.

# 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 (optional)
07 - 1 teaspoon balsamic vinegar (optional)

→ Sandwich Assembly

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

# Step-by-Step:

01 - In a large skillet over medium-low heat, melt the butter with the olive oil. Add the sliced onions, salt, and pepper. Cook, stirring occasionally, until deeply golden and caramelized, about 25-30 minutes. Stir in thyme and balsamic vinegar if using, and 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 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.

# Expert Advice:

01 -
  • The slow cooked onions develop a natural sweetness that balances the nutty sharpness of Gruyère perfectly
  • Its the kind of dinner that feels like an indulgent treat but comes together in under an hour
02 -
  • Low and slow is non negotiable for caramelized onions because rushing over high heat just burns them into bitterness
  • Grating your own cheese makes a huge difference since pre shredded cheese has anti caking agents that prevent smooth melting
03 -
  • Pat a paper towel over your caramelized onions before assembling to remove excess moisture that could make the bread soggy
  • Use a cast iron skillet if you have one for the most even heat distribution and best crust development
Go Back