Preheat the oven to 375. Grease or line a muffin tin.
In a large bowl, mix together the flour, baking powder, baking soda, salt, sugar, and cinnamon in a large bowl. Set aside.
In a separate bowl, mash the bananas, then add the egg, butter, vanilla, and yogurt (or sour cream) to the banana bowl.
Add the wet ingredients to the dry ingredients and mix well.
Spoon the batter into the muffin tin, using about 1/3 cup of batter for each muffin.
Combine the topping ingredients in a small bowl, then sprinkle over the batter.
Bake for 15-20 minutes, or until a toothpick comes out clean.