Pumpkin Hummus, Caramelized Onion and Fontina Cheese Pizzas

INGREDIENTS

• 1/4 cup olive oil, or as needed
• 2 pounds onions, thinly sliced
• 3 tablespoons brown sugar
• 1/3 cup balsamic vinegar
• 1/2 pound bacon
• 10 pieces lavash or other flatbread
• 5 cups pumpkin hummus
• 3 Granny Smith apples - peeled, cored and cut into matchsticks
• 5 cups shredded fontina cheese