For the Banana Bread Cake:

1. Preheat the oven to 350°F (175°C). Grease and flour a 9×13-inch baking dish.
2. In a medium bowl, whisk together the flour, baking soda, and salt.
3. In a large bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy.
4. Beat in the eggs, one at a time, followed by the vanilla extract.
5. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients.
6. Fold in the mashed bananas until just combined.
7. Pour the batter into the prepared baking dish and smooth the top.
8. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
9. Allow the cake to cool completely in the pan.

For the Cream Cheese Frosting:

1. In a large bowl, beat together the cream cheese and butter until smooth and creamy.
2. Gradually add the powdered sugar, beating until the frosting reaches your desired sweetness and consistency.
3. Spread the frosting evenly over the cooled cake.