To prepare a vegan double chocolate peanut butter banana cake recipe, first you need to prepare your ingredients. First, you'll need your bananas. You can use any type of banana, as long as it isn't too ripe. Place the banana slices in the bottom of the cake pan. Then, add the chocolate chips. Next, mix the ingredients together until they're evenly combined. Pour the batter into the pan and bake for 35 to 40 minutes or until the toothpick comes out clean. Allow to cool for 10 minutes before cutting into squares and serving.