Potato Candy or Peanut Butter Pinwheels

Peanut Butter Pinwheels
Originally published in the Liddabit Sweets Candy Cookbook

1 medium-size (4 to 5 ounces/100 to 150 g) potato, baked, cooled, and skinned (Yukon or russet varieties work best; don’t use any “waxy” potatoes, like the small red ones—it won’t turn out right!)
2 tablespoons (30 g) unsalted butter, at room temperature
4 to 6 cups (525 to 775 g) confectioners’ sugar, plus about 1 cup for dusting
1 teaspoon (5 g) pure vanilla extract
Cold milk, for thinning the dough if needed
1 cup (75 g) unsweetened shredded coconut (optional)
1 cup (180 g) creamy commercial peanut butter, such as Skippy
1 teaspoon (4g) fine sea salt

In a medium-size bowl, gently mash the baked potato with a fork, just enough so that there aren’t any big lumps. Add the butter, 4 cups of the confectioners’ sugar, and the vanilla, and mix well with a rubber spatula until smooth. The dough should be very stiff and sticky, almost like Play-Doh. If it’s too thick, add a little cold milk; if it’s too thin, keep adding confectioners’ sugar, 1/4 cup at a time, until it reaches the correct consistency. Add the coconut, if you’re using it, and mix to combine.
Divide the potato dough in half and form it into 2 balls. Wrap each one tightly in plastic wrap, and allow them to rest in the refrigerator for 1 hour.
Remove the balls of dough from the refrigerator. Generously and evenly sprinkle confectioners’ sugar over the surface of the prepared cutting board.
Roll out one ball of the dough into a rough 12-inch circle that’s about 1/2-inch thick. Use the spatula to spread half of the peanut butter evenly over the surface. Sprinkle 1/2 teaspoon of the sea salt evenly over the peanut butter, and starting at the edge closest to you, carefully roll up the dough into a log shape. Wrap the log in a piece of plastic wrap, or parchment or wax paper secured by twisting the ends together (this will help the log hold its shape). Chill in the refrigerator for 30 minutes. Meanwhile, assemble the second log.
Once the first log is firm enough to cut, use a sharp chef’s knife to slice it into 1/2-inch-thick rounds. Wrap each piece in wax twisting paper. Repeat with the second log. Store the pinwheels, layered between parchment or wax paper, in an airtight container in the refrigerator for up to 4 weeks.