Preheat the oven to 375 degree. Spray a baking dish (8 X 8 for six servings) with cooking spray or cover with parchment. Place the bananas (unpeeled) on a piece of foil and bake for 15 minutes. Remove and once cool, slice. It is fine is they are a bit mushy, in fact they should be soft. You can skip this step for faster prep but cooking the bananas will deepen the flavor and bring out more of their natural sweetness.