Cook 1 small potato cut into cubes until tender. Drain water and blend until smooth with a hand mixer. Measure out 1/2 cup of the potatoes and add to a large stand mixer bowl.

Add 3 cups powdered sugar and blend with stand mixer until well combined. It will be very sticky at this point. Add additional sugar 1 cup at a time until mixture resembles very thick frosting.

Turn out sugar and potato mixture onto a large sheet of waxed paper heavily dusted with powdered sugar. Add more sugar to the top of the dough and roll out to a rectangle 1/4" thick.

Spread evenly with peanut butter. Roll from the long side tightly. add more sugar to the wax paper before wrapping the sugar/peanut roll so the paper doesn't stick to the roll. Place in the refrigerator for several hours or overnight before unwrapping and cutting into 1" thick slices.