1 1/2 cup buttermilk (made by adding 1 tbsp lemon juice and topping it off with milk, then stirring and letting sit for 5 minutes before use)
4 oz cream cheese, softened to room temperature
1/4 cup salted butter, softened to room temperature
1 1/2 cup icing sugar
1/2 tsp vanilla
Mash the bananas using a stand or handheld mixer, and set aside.
Mix the flour, baking powder, cinnamon and salt, and set aside.
Beat the butter on high speed for about a minute, until smooth.
Add the sugar to the butter and cream together for about two minutes.
Beat the eggs and the vanilla together with the sugar and butter until well combined, then add in the mashed bananas and beat.
Add the dry ingredients alternating with the buttermilk in three portions while having the mixer on low speed, until everything has been incorporated.
Preheat the oven to 350 F.
Grease a round cake baking pan, and transfer all the batter into it spreading evenly. Bake for 45 – 50 minutes. Insert a toothpick into the center of the cake to make sure it comes out clean, before removing it from the oven and setting it out to cool.
Using a handheld or stand mixer, beat the cream cheese and butter together on high speed, until softened.
Add the vanilla and icing sugar, and using a rubber spatula or spoon mix well.
Beat the mixture on high speed for 2 minutes, before spreading the frosting on the cooled cake.
Serve the desired portion, and refrigerate the remaining for up to five days.