Preheat the oven to 180°C (350°F) and line an 8"x8" pan with baking paper.
Crush the Oreos and mix in the meted butter.
Press into the prepared pan and bake for 10 minutes.
Next, melt the marshmallows with the water on a medium heat.
Pour the mixture over the base (work quickly!)
Place in the fridge to set for 1 hour and 30 minutes.
Melt the chocolate and peanut butter together and spread over the marshmallow layer.
Return to the fridge for another hour before slicing.
You can you smooth Peanut Butter You could try this with dark or white chocolate. Allow the marshmallow layer to set completely before adding the chocolate peantu butter layer or it will sink and mix with the marshmallow layer.