Preheat oven to 350°F.
In a large mixing bowl, combine mashed bananas, butter, coconut oil, vanilla extract and egg. Whisk well.
In a seperate bowl, mix together instant coffee, baking powder, baking soda, salt, and oat flour. Mix in dry ingredients with wet ingredients until smooth. Stir in chopped walnuts.
Spoon out mixture into a bread pan and smooth out the top with a spatula. Place in the oven and bake for approximately 25 minutes or until edges begin to brown. Allow to cool before serving!