Add eggs, one at a time, and beat well after each egg is added. Add half of the dry ingredients (no need to be exact), then add the mashed banana. Next, add the remaining dry ingredients and finally, the vanilla.

Use a large oblong baking pan (9x13-inch) that has been sprayed with non-stick spray and lightly dusted with flour (shake out excess flour). Add batter and spread evenly in pan.

Bake for 35 to 40 minutes at 350°F. Cool completely and add coffee frosting.