Preheat oven to 375 F. Lightly grease muffin tin.
Combine flour, baking powder, salt, cinnamon and 1 tablespoon of the lemon rind.
Beat together bananas, eggs, brown sugar, butter, lemon juice and vanilla until blended.
Stir in dry ingredients until blended. Stir in blueberries just until combined. Spoon into prepared muffin cups, dividing batter equally.
For the topping, combine sugar and remaining lemon rind in small dish. Sprinkle evenly over the muffins.
Bake for 25-30 minutes or until golden.