Mix sugar, peanut butter, and butter in bowl, Knead with clean hands. Pinch and roll into 3/8 inch balls. Makes approx. 130 balls. Refrigerate.
Meanwhile melt 2 chocolate bars at a time in a double boiler pan on low heat, add 2 bars again after each has melted until 6 or 7 bars are melted.
Place mini muffin liners on a cookie sheet. Pour about 1 teaspoon of chocolate in each liner and refrigerate. After chocolate has hardened, place peanut butter ball in each liner and push down to make flat.
Melt the remaining chocolate bars and repeat covering with about 1 teaspoon melted chocolate or until peanut butter is covered. Refrigerate until chocolate is set. It is best to store peanut butter cups in a airtight container in the refrigerator.