Put the butter (or olive spread), golden syrup and cocoa in a bowl. Melt in a 900W microwave on HIGH for 20sec or until melted (or melt in a pan on a very low heat). Mix everything together.
Remove the mixture from the heat and stir in the crushed biscuits. Mix together well until thoroughly coated in the cocoa mixture, crushing down any large pieces of digestive biscuit as you do so.
Spoon the mixture into a greased 26x16.5cm (10x6½in) rectangular tin. Cool, cover and chill for 30min.
