Have a handful of speckled bananas lying around? Grab them and make this super moist, totally incredible banana cake with them immediately.
Preheat oven to 275 degrees F. Grease a 9x13 pan well. Mix together the banana and lemon juice in a bowl and set aside. In a large bowl, whisk together the flour, baking soda and salt. Set aside.
In the bowl of a stand mixer, add the butter and sugar. Cream together until light and fluffy, about 2 minutes. Add eggs, one at a time, mixing well after each addition. Mix in vanilla.
Add the flour and banana mixture alternatively to the creamed butter mixture. Add buttermilk and mix until just combined. Stir in bananas by hand.
Pour into the prepared pan and bake for an hour, or until a toothpick comes out clean. Remove from the oven and place in the freezer for 45 minutes. This will make the cake very moist.
Meanwhile, make the frosting. Cream together the butter and cream cheese. Add powdered sugar and beat until very light and fluffy, about 5 minutes. Spread on the cooled cake. Sprinkle with walnuts if desired.