Blend potatoes, butter and vanilla in large bowl with electric mixer on high speed or in food processor fitted with metal blade until smooth. Add 10x sugar, 1 cup at a time and mix until stiff enough to shape mixture should be slightly tacky to the touch. When you first begin adding sugar, mixture will liquify. But continue adding sugar and mixture will stiffen. (Caution) Do not attempt to make this recipe in rainy or humid weather because the candy will not harden.
Roll out candy between 2 sheets of wax paper into a rectangle about 18 inches long, 10 inches wide and 3/8 inch thick. Remove paper, spread evenly with peanut butter. Roll up. Cut roll in half crosswise to form two 9 inch long rolls. Wrap in paper chill 2 to 3 hours.