Preheat the oven to 400℉. Line a 12-count cupcake tin with cupcake liners.

In a large bowl using an electric handheld mixer, cream the softened butter and brown sugar on medium speed until combined. Add the eggs, vanilla, and mashed bananas and continue beating for 30 seconds.

In another smaller bowl, whisk together the flour, baking powder, and baking soda. Add into the wet ingredients alongside the milk and mix at low speed just until incorporated.

Scoop the batter into the lined cupcake tin, filling each cup to the top. Bake in a 400℉ oven for 5 minutes, then lower the temperature to 350℉ and continue baking for another 12-15 minutes or until a toothpick inserted into the center of each cupcake comes out clean. Let cool in the tin for 10 minutes before transferring to a wire rack to finish cooling completely before icing.

Using an electric handheld mixer, whip the softened cream cheese and butter at high speed until creamy. Add the powdered sugar, 1 cup at a time, mixing at low speed until fully incorporated. Lastly, blend in the milk, increase the speed to high, and beat for 30 seconds until fluffy.

Fill a piping bag fitted with your desired tip with the finished frosting. Pipe onto each cupcake, distributing it evenly between all the cupcakes. Sprinkle each cupcake with a pinch of cinnamon or nutmeg to garnish, if desired. Enjoy!