Peel and dice the potato. Boil in water until fork tender, about 10 minutes. Drain the excess water and mash with a hand mixer until smooth.
Mix in powdered sugar 1 cup at a time with a hand mixer. Depending on humidity and water content in the potato this can take 6-8 cups. The final result should look like that of shaggy dough. Slowly keep adding powdered sugar until the consistency is that of play-dough or putty
Spoon out onto a baking sheet lined with parchment or wax paper and dust generously with powdered sugar. Smooth out the potato dough using an offset spatula or rubber spatula about 1/4 inch in thickness.
Spread the peanut butter on top of the potato dough. Roll the dough on itself length-wise as if making cinnamon rolls.
Chill in the refrigerator for 2 hours. Slice into 1/2 inch pieces and serve.
If chilling overnight, allow the dough to rest on the counter for 10-15 minutes for easier cutting.