Preheat the oven to 350°F, fill a muffin tin with non-stick or foil liners.
Mix flour, baking powder, baking soda, salt and cinnamon in a separate bowl. Set aside.
Cream butter and sugar until light and fluffy.
Add eggs, vanilla and banana to butter and sugar. Mix until well-incorporated.
Add in half of the dry ingredients and mix a little. Then, add in buttermilk and mix and little. Then, add in the rest of dry ingredients and mix until just incorporated. Try not to over-mix.
Fill your muffin tin cups about 3/4 of the way full. I use a 1/4 cup measuring cup to measure up the batter.
Bake your cupcakes for about 18-20 minutes, or until a toothpick inserted comes out clean.