01 -
In a small pot of boiling water, cook the potato until tender. Drain and transfer to a bowl; mash until smooth and lump-free. Measure out 1/2 cup mashed potato and let cool slightly while still warm.
02 -
In a large bowl, combine the warm mashed potato with 2 cups of powdered sugar and stir until blended. Mix in the vanilla extract.
03 -
Gradually add remaining powdered sugar, 1 cup at a time, until a putty-like dough forms. Use a handheld electric mixer if the dough becomes too stiff to stir by hand.
04 -
Place dough on an 18×12 inch sheet of wax paper dusted with powdered sugar. Dust the top with more powdered sugar and roll out into a rectangle about 1/4 inch thick. Trim the edges to form a clean rectangle.
05 -
Spread an even layer of peanut butter over the dough. Starting from one long edge, roll tightly into a log. Wrap in wax paper and cut in half.
06 -
Place wrapped logs in a resealable plastic bag and refrigerate until firm, about 1 hour. Slice into 3/4-inch thick pieces before serving.