# What You'll Need:
→ Caramelized Onions
01 - 2 large yellow onions, thinly sliced
02 - 2 tablespoons unsalted butter
03 - 1 tablespoon olive oil
04 - 1/2 teaspoon salt
05 - 1/4 teaspoon freshly ground black pepper
06 - 1 teaspoon fresh thyme leaves (optional)
07 - 1 teaspoon balsamic vinegar (optional)
→ Sandwich Assembly
08 - 4 slices rustic country bread
09 - 4 ounces Gruyère cheese, grated
10 - 1 tablespoon unsalted butter, softened
# How-To Steps:
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, and cook 1 minute longer.
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 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 with melted cheese, about 3–4 minutes per side. Press gently with spatula for even toasting.
05 - Slice sandwiches in half and serve immediately.
