Place egg, butter, milk, baking powder, salt, sugar, grated peel, and bananas in high power blender. Grind thirty seconds or until ingredients are thoroughly mixed.
Add flour, and blitz to mix. You may need to use a spatula around the inside of the container to fully mix.
Pour batter into a greased 9x5 loaf pan.
Bake at 350F for 1 hour or until a toothpick inserted in the center comes out clean.