Caramelized Onion Gruyère Toast (Print Version)

Golden toasted bread topped with rich caramelized onions and melted Gruyère cheese for a savory delight.

# Components:

→ Caramelized Onions

01 - 2 medium yellow onions, thinly sliced
02 - 2 tbsp unsalted butter
03 - 1/2 tsp kosher salt
04 - 1/4 tsp freshly ground black pepper
05 - 1/2 tsp sugar (optional)
06 - 1 tsp balsamic vinegar (optional)

→ Sandwich

07 - 4 slices rustic sourdough or country bread
08 - 2 tbsp unsalted butter, softened
09 - 5 oz Gruyère cheese, grated
10 - Caramelized onions (prepared above)

# Directions:

01 - Melt butter in a large skillet over medium-low heat. Add sliced onions, salt, and pepper. Cook, stirring occasionally, for 25–30 minutes until onions are deeply golden. Stir in sugar and balsamic vinegar if using; cook an additional 2–3 minutes. Remove from heat.
02 - Spread softened butter on one side of each bread slice. Place two slices butter-side down, distributing half the grated cheese evenly. Top with caramelized onions and remaining cheese. Close each with the remaining bread slices, butter-side up.
03 - Heat a nonstick skillet or griddle over medium heat. Cook sandwiches 3–4 minutes per side, pressing gently, until bread is golden and cheese melts. Reduce heat if bread browns too quickly.
04 - Slice sandwiches and serve immediately.

# Expert Advice:

01 -
  • The caramelized onions become almost sweet and jammy, turning a simple sandwich into something that tastes like you spent hours in the kitchen.
  • Gruyère has a nutty depth that makes you wonder why you ever settled for basic cheddar.
  • It's elegant enough to serve to people you want to impress, but easy enough that you'll make it on random Tuesdays just for yourself.
02 -
  • The onions need time—really do let them cook for nearly half an hour on low heat, because rushing this step with higher heat will give you brown onions instead of caramelized ones, and the difference is everything.
  • Grate your own Gruyère instead of using pre-shredded if you can; it melts more smoothly without the anti-caking agents.
03 -
  • If you want to get ahead, caramelize your onions earlier in the day or even the day before—they actually taste better when the flavors have time to settle, and reheating them gently brings everything back to life.
  • Press the sandwich gently as it cooks, not aggressively; you're helping the cheese melt evenly, not squashing all the air and texture out of the bread.
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