Whenever I make this candy, people are amazed to learn that it is made with a potato. It is very sweet and rich and is best accompanied by a tall glass of milk. It's an old family recipe that my mother always made at Christmas time. I'm not sure from where it originated but suspect our Irish or Pennsylvania Dutch heritage.
- Combine mashed potato, powdered sugar, milk and vanilla in a medium bowl.
- Add powdered sugar a little at a time until the mixture reaches the thickness of pie dough. You will need to use clean hands to kneed the dough until everything is fully incorporated. Use a little more or less of the powdered sugar until the desired texture is met. If it becomes too stiff, add one tiny drop of milk at a time until the desired texture is met. I wish it were more of an exact science, but it's not. :).
- Spread waxed paper onto your work surface and liberally dust with powdered sugar. I use the waxed paper to assist in rolling. Please note if you use a plain work surface dusted with powdered sugar, it's much more difficult to roll it up due to the dough's tendancy to stick to the flat surface (which can result in the dough tearing).
- On the waxed paper, roll the dough into a circular shape until 1/4-inch thick.
- Spread peanut butter evenly over the dough up to 1/2 inch from the edge of the circle.
- Carefully roll up like a jelly roll, using the waxed paper as a helpful tool.
- Place onto a cookie sheet covered with a clean sheet of waxed paper.
- Refrigerate uncovered until fully chilled (about three hours), and the outside of the roll becomes crusty.
- Slice roll into 1/4-inch pieces.
- Store candy arranged flat in an air-tight container with waxed paper between each layer for up to two weeks (or probably more--it's never lasted that long around our house). The candy will harden and become more brittle as it ages, and this is perfectly fine.
- The candy can sit at room temperature for up to three hours before becoming soft. To reach original texture, replace in refrigerator.