Line 13" x 9" pan with aluminum foil.
Place 1 cup of peanut butter chips in a medium bowl, set aside.
In second medium bowl, blend melted butter, cocoa, and vanilla until smooth. Add 1 cup peanut butter chips (the rest of the peanut butter chips).
In a heavy 4 qt. saucepan, combine sugar, marshmallow crème, and evaporated milk.
Cook, stirring constantly over medium heat until mixture comes to a rolling boil. Boil and stir 5 minutes. Remove from heat.
Immediately add one-half of hot mixture to bowl with peanut butter chips only. Pour remainder into cocoa mixture; Stir to blend. (This is where it is helpful to have a second set of hands to stir one mixture while you stir another mixture.)
Beat peanut butter mixture until chips are completely melted; spread evenly in prepared pan.
Beat cocoa mixture until chips are melted and mixture thickens. Spread evenly over top of peanut butter layer.
Cool; remove from pan. Remove foil. Cut into squares. Store in an airtight container in a cool, dry place.