Preheat the oven to 350 degrees. Coat a 9 x 13 baking dish with cooking spray.
Make the cake by creaming the butter and sugar together with a mixer until light and fluffy. Add the eggs, sour cream and vanilla extract; beat until creamy.
Combine the flour, baking soda, cinnamon and salt together in a separate dish; mix well.
Gradually add the flour mixture to the butter mixture until just combined. Add the well mashed banana and mix until combined. Pour the batter into the prepared baking dish.
Bake for 28-30 minutes, or until a tester inserted in the center comes out clean. Remove from the oven and allow to cool on a wire rack completely.
Make the cream cheese frosting by beating together the cream cheese, butter and vanilla together until creamy. Gradually beat in enough powdered sugar to achieve desired consistency.
Spread the frosting evenly over cooled cake, cut and serve. Enjoy.
Cover and store the remaining cake in the refrigerator.