Pre-heat oven to 180C. Arrange Doritos on a sheet of greaseproof paper on an oven proof tray.
Cover with marshmallows and place in the oven for 7 minutes, until they start to melt. Remove and put under the grill, so the marshmallows crisp and brown.
Melt the chocolate in a microwave and drizzle over the marshmallows!
Add smashed or crumbled bisbuits and some extra crushed Doritos if you fancy. Serve with crème fresh or double cream for dipping and maybe some strawberries!