Cream the butter and sugar in a mixer bowl.
Add the eggs, milk and vanilla. Mix till blended.
Stir the baking soda and salt into the flour, then add the dry ingredients to the wet. Mix well.
Add in the bananas. Mix well.
Spread into a greased 10″x15″ pan. Bake at 350 degrees for 25-30 minutes or until a toothpick comes out clean.
Cool completely before frosting.