My grandmother gave me this recipe too!  She used to make it at Christmas when we would come visit, and I could have eaten the whole thing!  I was amazed to find how easy it is to make.  It does get kind of mushy if it stays out of the fridge too long.  Just sayin’…

1 c. peanut butter flavored chips
1 c. semi-sweet chocolate chips
1 (14-oz.) can sweetened condensed milk
1 t. vanilla extract 

In 2-cup glass measure, combine peanut butter chips and 2/3 cup sweetened condensed milk; cook on 100% power 1-1½ minutes, stirring after 1 minute, until chips are melted and mixture is smooth. Stir in ½ t of vanilla; spread evenly onto waxed paper-lined 8 inch square pan.  In 2 cup glass measure, combine remaining milk and chocolate chips; repeat above microwave procedure. Stir in remaining ½ t vanilla; spread evenly on peanut butter layer. Chill 2 hours or until firm.  Turn onto cutting board.  Peel off paper and cut into squares. Store covered in refrigerator.