Preheat oven to 350F. Prepare three 8-inch pans by spraying with pan spray, lining the bottom with parchment paper, and then dusting the sides with flour. Set aside. (You can also make 20 to 24 cupcakes – line cupcake pan with cupcake liners.)

In a medium bowl, sift together the flour, baking powder, cinnamon, baking soda, and salt. In a separate bowl, add the lemon juice to the milk if you are making your own buttermilk and set it aside. Otherwise, measure out the buttermilk and let come to room temperature.

In the bowl of a stand mixer, cream the butter, light brown sugar and granulated until light and fluffy, about 3 minutes on medium. Stop the mixer and scrape down the sides of the bowl. Mix for 30 seconds more. Add the eggs, one at a time, mixing to incorporate after each addition. Add the vanilla the mashed bananas. Mix until incorporated.

Add ⅓ of the flour mixture with the mixer on low. Mix just until combined. Add ½ of the buttermilk and mix until combined. Add another ⅓ of the flour, mix; add the remaining buttermilk and mix then add the last of the flour and mix for 30 seconds on medium speed.

Divide the batter evenly between the pans. Bake for 27 to 30 minutes or until a toothpick inserted into the center comes out clean. Run a knife or offset spatula around the sides of each pan. Allow to cool for 10 minutes in the pan then turn out onto a cooling rack. Cool completely before icing.

Assemble the cake: Spread icing on the top of one cooled layer, add another layer of cake, spread icing on top, and then add the last cake layer. Ice the top and sides of the cake with a thin layer of icing and refrigerate for 15 to 30 minutes, until the icing has hardened up a bit. Apply more icing to the sides and top and smooth with an offset spatula or bench scraper. Decorate as desired.