Preparation Preheat oven to 250°F. Whisk flour, sugar, baking powder, and salt in large bowl to blend. Whisk buttermilk, eggs, and butter in medium bowl to blend. Gradually whisk buttermilk mixture into flour mixture just until blended (do not overmix; some small lumps may remain). Heat griddle or 2 large nonstick skillets over medium heat. Brush griddle lightly with oil. Working in batches, pour batter by scant 1/4 cupfuls onto griddle. Top each pancake with 4 banana slices. Cook until bottoms brown and bubbles form, about 2 minutes. Turn pancakes over and cook until bottoms brown and banana slices caramelize, about 2 minutes. Transfer pancakes to baking sheet and place in oven while cooking remaining pancakes. Transfer pancakes to plates. Serve with warm maple syrup.