Combine peanut butter, butter and vanilla in a medium mixing bowl. Add graham cracker crumbs, powdered sugar, and mix well. Roll into 1/2" balls, place on a baking sheet and freeze until firm, at least 30 minutes.
Place Candy melts in a medium microwave safe bowl, heat at 30 second intervals, stirring after each, until smooth and melted.
Using a toothpick, dip frozen peanut butter balls into melted chocolate, leaving the top exposed. Place on sheets of wax paper until chocolate is set.