Preheat the oven to 350 degrees. Grease an 8x8 pan.
Beat the butter and sugar until blended. Add the egg and vanilla and mix well. Add the flour, baking powder, salt and graham cracker crumbs.
Press 2/3 of the dough into the bottom of the prepared pan. Press the chocolate bars side by side on top of the dough.
Melt the peanut butter for about 30 seconds in the microwave and drizzle it over the chocolate bars.
Heat up the marshmallow cream in the microwave (in a new bowl not the container!) for 20 seconds and spread over the chocolate and peanut butter.
Roll the remaining 1/3 dough on a floured wax paper. When you’ve made an even square, gently peel it off and press it on top of the marshmallow cream.
Bake for 30 minutes or until golden brown on top. Let cool.