In a large skillet over medium heat, add the butter and swirl about the pan until melted.
Add the marshmallows and stir with a wooden spoon until melted.
Remove from heat.
One cup at a time, stir in the cereal. (You may need to transfer this part of the recipe to a large bowl if your skillet is not large enough).
Stir in the peanut butter candy.
Spray the back of a large metal spoon with non stick cooking spray and use it to press the marshmallow mixture into an even layer in the prepared pan. Set aside.
Bring the cream to just a simmer over medium heat - bubbles will be appearing at the edges.
Remove from heat, add the peanut butter and chocolate.
Let stand for 5 minutes.
Stir until completely smooth.
Let sit for 15 minutes before pouring over marshmallow treats.
Place in fridge for 15 minutes minimum to set.
Meanwhile, in a bowl, whisk together the peanut butter, confectioners' sugar and cream until smooth. If needed add more or less sugar or cream.
Using a pastry bag or a resealable bag with a hole cut in the corner, pipe the peanut butter onto the glaze layer into zig zags or whatever your heart desires.