# What You'll Need:
→ For the 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 (optional)
07 - 1 tsp balsamic vinegar (optional)
→ For the Sandwiches
08 - 4 slices rustic country bread
09 - 4 oz Gruyère cheese, grated
10 - 1 tbsp unsalted butter, softened
# Directions:
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 if using, 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 generously 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 cheese melted, about 3–4 minutes per side. Press gently with spatula for even toasting.
05 - Slice each sandwich in half and serve immediately.