Preheat oven to 350°F. Spray a mini muffin pan with cooking spray. You can also use liners, if you want.
Stir peanut butter, oil, banana, and honey. Stir in flour, baking soda, and baking powder until combined. Evenly distribute between the cavities of your muffin pan. Bake 10-20 minutes, until browned and a toothpick inserted in the center comes out clean. Cool completely before frosting.
Banana frosting: stir mashed banana and peanut butter together. Frost. Serve immediately (the frosting will brown as the cupcakes sit).
PB Cream Cheese frosting: stir peanut butter and cream cheese. Frost. Store in refrigerator.