Grown Up Grilled Cheese Sandwiches with Balsamic onions, Prosciutto, and Sliced Pears | Seven Hills

Ingredients

• 1 medium red or white onion, sliced into thin wedges
• 2 tablespoons unsalted butter
• Sea salt
• 1 tablespoon balsamic vinegar
• Freshly ground black pepper
• 4 slices, artisanal bread
• 2 tablespoons mayonnaise
• 1.5 cups mixed grated cheeses – gruyere, jack, sharp white cheddar
• 1 ripe, but firm, pear sliced
• 2 slices prosciutto