Caramelized Onion & Gruyère Grilled Cheese (Printer-friendly)

Sweet caramelized onions and nutty Gruyère melted between crispy, golden country bread slices.

# What You'll 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

# 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 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. Evenly spread caramelized onions on two slices. Top each with half the grated Gruyère. Place remaining bread slices on top to close sandwiches.
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 the pan and cook until golden brown and cheese is melted, about 3–4 minutes per side. Press gently with spatula to ensure even toasting.
05 - Slice sandwiches in half and serve immediately.

# Expert Hints:

01 -
  • The slow caramelized onions turn impossibly sweet, creating a jammy texture that perfectly balances the rich cheese
  • Gruyère brings this incredible nutty depth that regular cheddar just cant match, plus it melts beautifully
  • This feels fancy enough for company but comes together in under an hour with mostly pantry staples
02 -
  • Rushing the onion caramelization is the biggest mistake you can make, those dark brown bits are where all the flavor lives
  • Low and slow heat is non negotiable for the onions, high heat will burn them before they properly caramelize
  • Grating your own cheese makes a huge difference in melting quality compared to pre-shredded varieties
03 -
  • Make a double batch of caramelized onions and use them throughout the week for burgers, pizza, or pasta
  • Let the sandwiches rest for about 30 seconds after cutting so the cheese sets slightly and doesnt ooze out completely
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