Caramelized Onion & Gruyère Grilled Cheese (Printable Version)

Sweet caramelized onions and nutty Gruyère melted between crispy golden country bread for a gourmet twist on a classic comfort sandwich.

# What You Need:

→ Caramelized Onions

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

→ Sandwich Assembly

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

# Step-by-Step Guide:

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 generously on the outside of each sandwich slice.
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 each sandwich diagonally in half and serve immediately while hot.

# Expert Advice:

01 -
  • The way the nutty Gruyère plays against those sweet, jammy onions creates flavors that feel like something you'd order at a bistro
  • Once you master the onion technique, you'll find yourself adding them to everything from burgers to pasta
02 -
  • Rushing the onions over high heat will make them bitter instead of sweet, so resist the urge to crank up the stove
  • Grating your own cheese makes a huge difference since pre-shredded cheese has anti-caking agents that prevent smooth melting
03 -
  • Low and slow is the golden rule for onions that caramelize instead of burn
  • Mayo instead of butter on the outside creates an even crispier crust and won't burn as easily
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