Paula Deen's Yummy Banana Cream Cake

¾ c. butter, softened1 ½ c. sugar3 large eggs2 c. mashed ripe bananas1 t. vanilla2 ¼ c. flour1 ½ t. baking powder½ t. baking soda½ t. salt¼ c. plus 2 T. whole buttermilk1 (3.4-oz.) box banana cream instant pudding mix2…