BANANA CAKE: In a stand mixer, cream butter with sugar until light & fluffy. Scrape bowl. Add eggs, sour cream, vanilla, & mashed bananas. Scrape bowl.
Combine flour, baking soda, & salt & slowly add to mixture. Mix until just blended.
Spread light fluffy mixture onto a 10x15" jelly-roll pan that has been lightly greased.
Bake at 350*F for 20-25 minutes or until cake springs back when touched & is starting to brown on the top.
CREAM CHEESE FROSTING: Beat cream cheese with butter until light & fluffy. Add powdered sugar all at once until just mixed.
Spread over cooled banana bars. Keep the tip of your spatula down, don't lift up or you might pull up cake with it & leave crumbs in your icing. Enjoy!