01 -
In a large bowl, beat the mashed potato, milk, vanilla, and salt with an electric mixer on medium speed for 2 minutes.
02 -
Gradually mix in powdered sugar, 1 cup at a time, until a dough has formed. Add more sugar in 1 tablespoon increments if necessary, ensuring the dough is thick and slightly thicker than cookie dough.
03 -
Form the dough into a ball and dust it with powdered sugar. On a sheet of wax or parchment paper, roll the dough into a rectangle approximately 1/8-inch thick. Trim the rectangle to 10x12 inches.
04 -
Generously sprinkle powdered sugar over the surface of the dough. Place another sheet of parchment paper on top, invert the rectangle, and carefully remove the original parchment sheet.
05 -
Spread the peanut butter evenly over the surface of the dough.
06 -
Tightly roll the dough from the long side to the long side using the parchment paper to guide it, forming a jelly-roll style log.
07 -
Wrap the rolled dough in parchment paper and freeze for 1 hour. Cut the roll into 1/4-inch thick slices before serving.
08 -
Store leftover candy in an airtight container in the refrigerator.