01 -
Place the peeled potato in a small saucepan and cover with water. Boil until very tender, 12-15 minutes, then drain well and mash until smooth. Measure 1/4 cup and cool completely.
02 -
In a medium bowl, stir the cooled mashed potato with vanilla and salt until smooth.
03 -
Add powdered sugar 1 cup at a time, stirring well after each addition. Continue until the mixture becomes a soft dough that is no longer wet or runny.
04 -
Dust parchment paper with powdered sugar. Knead the dough briefly, then roll it into a rectangle about 1/4 inch thick.
05 -
Spread the peanut butter in a thin, even layer over the dough, leaving a 1/2-inch border around the edges.
06 -
Roll the dough tightly from the long side, using the parchment to help lift and guide it. Wrap the log in plastic wrap.
07 -
Refrigerate for at least 30 minutes, or until firm. Slice into 1/4-inch pinwheels and store chilled.