Easy Peanut Butter Cake...From a mix. Be The First To Review By Mandica12182 recipe Posted by Mandica12182 I know this is probably a given and it's probably been posted on here before. But my DH actually loved this cake and can't wait for me to make it again, and he's quite the critic. Easy Peanut Butter Cake...From a mix. Ingredients 2 boxes of butter recipe yellow cake mix 1 cup of creamy/or chrunchy peanut butter (your choice) Instructions Make the mixes as directions on box tell you to and just add 1 cup of peanut butter....It's that simple. The peanut butter of course makes the cake more dense and moist and also acts like an extender and makes more cake!!