Cream the sugar and the butter together. Sift the flour in and mix. Add the egg yolk and vanilla essence. Mix and add the fruit and chocolate.
Roll into a sausage and wrap in clingfilm. Leave in the fridge for an hour or more.
When you want a cookie or two place in a oven at 180C or Gas Mark 5. For chewy cookies wait till they are golden brown and then remove from the oven, leaving them on the baking tray for 5 minutes.