01 -
Beat cooled mashed potatoes and butter with electric mixer until smooth. Stir in vanilla extract.
02 -
Gradually add powdered sugar 1 cup at a time, mixing well between additions, until mixture reaches cookie dough consistency.
03 -
Working quickly, place mixture on powdered sugar-dusted wax paper. Dust top with more sugar and roll to ¼ inch thick rectangle.
04 -
Spread peanut butter over rolled dough, leaving ½ inch border.
05 -
Tightly roll into log shape. Wrap in plastic wrap, tucking ends under.
06 -
Refrigerate 10 minutes to set. Unwrap and cut into ¼-½ inch slices to serve.