Preparation

• Peel and slice the potato. Cook in a small pan of water until it is very tender. Drain off the water.
• Place the potato in the mixing bowl of a stand mixer or mix by hand with a wooden spoon. Add the butter, vanilla, and salt. Using a potato masher, mash the potato until it is free of all lumps.
• Add the powdered sugar about 2 cups at a time, while mixing on low speed and using the whisk attachment. Continue adding the sugar until the candy mixture becomes thick and pliable yet just slightly sticky.
• Lay a piece of wax or parchment paper on a countertop and sift powdered sugar heavily on the paper. Place one-third of the candy mixture on the paper and form it into a ball. Sift additional powdered sugar on top of the formed ball.
• Place a piece of wax or parchment paper over the top of the ball and slightly flatten the ball with the palm of your hand. Using a rolling pin, roll the candy out to no more than ¼" in thickness, rolling it into a rectangular shape. Remove the top piece of paper.
• Place a large heaping spoonful of peanut butter onto the candy. Spread it out, stopping about ¼" from the edges of the candy.
• Using a sharp metal spatula, knife, or bench scraper, roll the candy into a roll, working from left to right. Place the roll onto a cookie sheet lined with foil, wax, or parchment paper.
• Roll the remaining two rolls and place on the cookie sheet. Transfer to a freezer for 10 minutes until very cold before slicing.
• Slice candy into ¾" slices, discarding or eating the end pieces. Store in an airtight container.
• Yields about 2 pounds.