- Preheat oven to 375 degrees F. Spray muffin tin with non-stick cooking spray. 
- In a medium bowl stir together flour, baking powder, baking soda, cinnamon and salt.  
- With an electric mixer, mix together mashed banana, egg, sugar, butter and vanilla. Slowly add in dry ingredients.  
- Spoon mixture into muffin tins filling about each tin about 1/2 way.  
- In a small bowl add flour, cinnamon, brown sugar and butter for the topping. Use a fork to mix together until it forms into crumbles. Sprinkle on top of each muffin.  
- Bake for 15 minutes. Let the muffins cool in tin for 10 minutes before removing and place on wire cooking rack.