Measure peanut butter chips into one mixing bowl and chocolate chips into second bowl; set aside.
Butter an 8-inch square pan.
Combine evaporated milk, butter, sugar and Marshmallow Creme in a heavy 2 3/4-quart saucepan. Cook over medium heat until mixture begins to boil, stirring constantly; continue cooking and stirring 5 minutes.
Remove from heat; stir in vanilla extract. Immediately add about one-half of hot mixture to chocolate chips, stirring until completely melted; pour into prepared pan.
Add remaining hot mixture to peanut butter chips, stirring until completely melted.