Preheat the oven to 275°
Spray the sides of a 9x13 baking pan with Baking Joy. If you do not have this spray, line the sides of the pan with a thin layer of butter and cover the butter with a thin layer of flour. Line the bottom of the pan with parchment paper.
Mash about 2-3 bananas in a bowl. Add the lemon juice and stir. Set the mixture to the side.
Sift the dry ingredients (flour, baking soda, and salt) together in a large bowl. Set the bowl to the side.
Cream unsalted butter and sugars together in a stand mixer using the paddle attachment or use an electric hand-mixer.
Add in the eggs one at a time and vanilla extract. Mix on medium speed until the ingredients are light and fluffy.
Set the mixer to the lowest speed and slowly add the flour mixture and buttermilk. Alternate these ingredients beginning with the flour and ending with the flour.
Slowly mix in the mashed bananas.
Pour the batter into your prepared baking dish. Spread the batter evenly using a spatula.
Place the baking sheet in the oven. Bake at 275° for about 45-50 minutes. Insert a toothpick to see if the cake is baked completely. The cake is ready if the toothpick comes out clean. Allow the cake to cool completely before adding the cream cheese frosting.