Preheat oven to 350° F. Grease two 6-cup donut tins and set aside.
In a mixing bowl, combine mashed bananas, peanut butter, coconut oil and honey. Mix until well combined. Add egg and mix until incorporated. Stir in flour and baking soda just until combined.
Transfer batter to prepared donut tins. Bake at 350° F for 15 to 20 minutes or until a toothpick inserted in one of the donuts comes out clean. Let donuts cool for a few minutes in the pan before transferring them to a wire rack to cool completely.
Peanut Butter Frosting
In a mixing bowl, combine greek yogurt and peanut butter until smooth and creamy. Use a knife or offset spatula to spread the frosting on the cooled donuts. Sprinkle with crushed biscuits if desired and serve to your pup!
Peanut butter: Use a natural creamy peanut butter that is no-stir (doesn't separate in the jar). Check the ingredients. It's best not to give your pups peanut butter with added sugar and palm oil.Store dog donuts in an airtight container in the refrigerator for 3 days.Freeze dog donuts (unfrosted) in an airtight container for up to one month. Defrost in the refrigerator before frosting and serving.