Line a 13x9x2-inch pan with foil.
Place 1 cup peanut butter chips in medium bowl; set aside.
In a second medium bowl, blend 1/4 cup melted butter, cocoa and vanilla until smooth; add remaining 1 cup peanut butter chips.
In a heavy 4 quart saucepan, combine sugar, marshmallow cream, evaporated milk and 1/4 cup butter. Cook, stirring constantly over medium heat until mixture comes to a rolling boil. Cook and continue stirring 5 minutes.
Remove from heat. Immediately add half of hot mixture to bowl with peanut butter chips only. Pour remainder into cocoa mixture; stir to blend.
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 airtight container in a cool dry place.