Caramelized Onion & Gruyère Grilled Cheese (Printable)

Gourmet grilled cheese with sweet caramelized onions, nutty Gruyère, and crispy country bread. French-inspired comfort in every bite.

# 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

→ Sandwiches

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

# How-To Steps:

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 to 30 minutes. Stir in thyme and balsamic vinegar if using, and 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 the 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 to 4 minutes per side. Press gently with a spatula to ensure even toasting.
05 - Slice sandwiches in half and serve immediately.

# Expert Tips:

01 -
  • The combination of sweet onions and nutty Gruyère creates layers of flavor that feel like something from a bistro, not your kitchen counter
  • Once you master caramelized onions, you will want to put them on everything from burgers to pasta
02 -
  • Rushing the caramelization process is the biggest mistake, so keep your heat low and let the onions do their thing
  • Grating your own cheese makes a huge difference in how evenly it melts compared to pre shredded versions
03 -
  • Low and slow is your mantra for caramelized onions, you cannot rush them without sacrificing flavor
  • Grating the cheese yourself takes an extra minute but creates that perfect, velvety melt you want
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