1. Take the cooked/purchased cake and put it in a food processor and pulse/grind it up until it's the consistency of dirt ( don't turn it into powder ) 2. Put that in a bowl and then add the peanutbutter a spoon full or two at a time and mix it well with the ground up cake. 3. Just add enough PB until the ingredients are moist enough to be able to form balls that hold together. How much PB you use will depend on the size of the cake you ground up. Variation 1: use cream cheese instead of PB Variation 2: I melted down some PB and dipped the cake balls into them.