Steps
- Mix ¼ cup of plain cold mashed potatoes with 1½ teaspoons of vanilla extract. Gradually stir in 3 cups of icing sugar, using enough to form a soft dough that holds together.
- Knead briefly on an icing-sugar-dusted surface until smooth. Roll out on parchment into a 14 × 8in / 35 × 20cm rectangle.
- Warm ⅓ cup of crunchy peanut butter briefly in the microwave until spreadable. Spread over the dough and roll from a long edge into a log. Refrigerate for 1 hour.
- Remove the parchment and cut into ½in / 1cm slices.