Roll out the potato candy to a 12-by-10-inch rectangle (about ¼-inch thick), dusting the top with powdered sugar if it becomes sticky. Spread the peanut butter in an even layer over the potato candy.
Samuel’s Sweet Shop in Rhinebeck, N.Y. — co-owned by Paul Rudd, Jeffrey Dean Morgan and Hilarie Burton — serves a variety of old-school candies ... these peanut-butter-packed blondies ...