So this recipe is one I tried out this week and it's actually from here on charisstoma's Livejournal. I've converted it to UK measurements and UK ingredients and it's not quite the same, but if you want the US version, just click the link :).

No Bake Chocolate Peanut Butter Bars
Ingredients:

No Bake Chocolate Peanut Butter Bars
Ingredients:
- 227g peanut butter
- 227g butter
- 400g (1 pack) digestive biscuits
- 150g caster sugar
- 300g dark chocolate (or a mixture of milk and dark if you prefer - go with your taste)
- 4 Tbsp peanut butter
- In a heavy base saucepan melt the peanut butter and butter over a low heat.
- Crumb the digestive biscuits either in a food mixer or in a bag with a rolling pin.
- Mix the caster sugar through the biscuit crumb.
- Add the melted peanut butter and butter and combine well.
- Press into a 9''x13'' greased pan (I used a throw away tin foil tray and it worked really well).
- Melt the chocolate and peanut butter in the microwave (or on the hob).
- Pour the chocolate mixture over the biscuit base and chill in the fridge for at least 1hr.
These are very rich so I cut them into little squares. They taste a bit like Reeses Peanut Butter Cups, but with more bite to them because of the biscuit base. I just gave what was left over to the guys that work in the place next to our house because we couldn't eat it all :).