Preheat oven to 350°F (175°C) and grease a 9x13 inch baking pan. Whisk together flour, baking soda, and salt in a bowl.

In a separate large bowl, cream together butter and granulated sugar until light and fluffy. Beat in eggs one at a time, then stir in vanilla extract.

Add the mashed bananas to the wet ingredients and mix well. Gradually add the dry ingredients alternately with the buttermilk, starting and ending with the dry ingredients, mixing until just combined.

Pour the batter into the prepared pan and bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean. Let the cake cool completely on a wire rack.

In a large bowl, beat the softened cream cheese and butter together until smooth. Gradually add the powdered sugar, mixing until creamy.

Stir in the vanilla extract. If the frosting is too thick, add milk one tablespoon at a time until desired consistency is reached.

Once the cake is completely cool, spread the cream cheese frosting evenly over the top. Serve and enjoy.