Preheat oven to 180c. Grease and line a rectangular tin (20x30 centimeters).
Base: Rub butter and flours together to form a dough. Add sugar and chopped peanuts. Add water if needed to bring together. Press into the tin. Bake for 25 minutes then cool.
Peanut layer: put butter and peanut butter in a pan and melt down. Add icing sugar and mix together. Pour over shortbread and chill in fridge for 2 hours.
Pour caramel over the peanut layer and then chill for 1 1/2 hours.
Melt dark chocolate and then pour over caramel layer. Chill for 2 hours, then decorate!
