Preheat your oven to 350°F (175°C). Grease and flour your 9x13-inch baking pan.
In a large mixing bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. Set aside.
In another bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs, one at a time, mixing well after each addition. Then mix in the vanilla extract.
Fold in the mashed bananas gently until fully combined.
Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk, mixing until just combined.
Pour the batter into the prepared baking pan and spread evenly. Bake for 30-35 minutes, or until a toothpick comes out clean.
Remove the cake from the oven and let it cool in the pan for about 10 minutes, then transfer to a cooling rack.
For the frosting, beat together cream cheese and butter until smooth. Gradually add confectioners sugar, vanilla extract, and a pinch of salt, beating until creamy.
Once cool, frost the cake generously with the cream cheese frosting.