Preheat your oven to 350 degrees F. Beat together your sugars and butter, until fluffy, about 3 minutes, then add in the mashed bananas, then the eggs, one at a time, then the extract, scraping down the sides of the bowl as needed to be sure all of the ingredients are well combined.
Whisk together the flour, baking powder, baking soda, salt, and cinnamon. Add 1/3 of the dry mixture to the banana mixture, followed by 1/4 cup of buttermilk, another 1/3 of the dry mixture, the remaining 1/4 cup of buttermilk, and finally the remaining 1/3 cup of dry mixture (this helps the batter to combine easier without over-beating).
Drop the batter into your prepared muffin cups (about 2 teaspoons for mini-cupcakes, or 2-3 tablespoons for regular sized cupcakes).
Bake for 10-12 minutes for miniature cupcakes, for 15-18 minutes for regular sized cupcakes. Allow to cool before frosting (recipe follows). These will keep well in an airtight container, unfrosted, for up to a week at room temperature, or frosted and refrigerated in an airtight container, for up to 3 days.
Tom Cooper | Elite.