Pumpkin Butter Tart with Caramelized Onions and Smoked White Cheddar

Makes: 8-10 appetizer servings (2 medium tarts or 1 large tart) Ingredients For the caramelized onions: 1 1/2 tablespoons extra virgin olive oil 2 1/2 cups sliced onions (1/4-inch thickness) Kosher salt Freshly ground black pepper