# 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
→ Sandwiches
08 - 4 slices rustic country bread
09 - 4 oz Gruyère cheese, grated
10 - 1 tbsp unsalted butter, softened
# How-To:
01 - Melt butter with olive oil in a large skillet over medium-low heat. Add sliced onions, salt, and pepper. Cook, stirring occasionally, until onions are deeply golden and caramelized, about 25-30 minutes. Stir in thyme and balsamic vinegar, if using, and 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 evenly 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 and cheese is melted, about 3-4 minutes per side. Press gently with spatula for even toasting.
05 - Slice sandwiches in half and serve immediately.