Preheat oven to 180°C. Line your muffin tin with cupcake papers - I did a combination of mini and full cupcakes.
Sift together flour and baking powder; set aside.
In a medium bowl, stir together the peanut butter, mashed banana, egg, and water until combined.
Stir in the flour mixture, and mix until smooth. Scoop into muffin pans.
Bake mini cupcakes for 8-10 mins and the big cupcakes for 15-20 mins.
Peanut Butter and Banana Frosting
Cream the peanut butter and cream cheese together..
Add in the mashed banana and continue mixing for 2 minutes until well mixed (please note this won't be as light and fluffy as normal buttercream with sugar).
Spoon icing into a piping bag and pipe swirls onto the cooled cupcakes.
Enjoy with your pooch!
Notes
Please double check your peanut butter does not contain the artificial sweetener xylitol as this is toxic to dogs. This recipe makes enough for 3 large cupcakes and 5 mini cupcakes.