Grease or butter a 13 x 9 x 2 pan. Place 1 cup of peanut butter chips in medium bowl. In second bowl, blend 1/4 cup melted butter, cocoa, and vanilla until smooth, add 1 cup of peanut butter chips.
In heavy 4-quart pan, combine sugar, marshmallow cream, evaporated milk, and 1/4 cup butter. Cook, stirring constantly over medium heat until mixture comes to a rolling boil, boil and stir for 5 minutes.
Remove from heat, immediately add 1/2 of hot mixture to bowl with the peanut butter chips. Pour the other half into the cocoa mixture, stir to blend.
Beat the peanut butter mixture until all the chips are melted. Spread evenly into pan
Beat cocoa mixture until chips are melted and mixture thickens. Spread over the peanut butter layer.
Cool, cut into squares, remove from pan and store in airtight container in cool dry place.