In a large bowl, crush the Digestive biscuits into medium-sized chunks. Add the chopped Crunchie pieces and briefly mix.
Break the milk chocolate into pieces and add it to a saucepan along with the butter, golden syrup and cocoa powder. Put over low heat and stir gently until fully melted.
Pour the melted mixture into the bowl with the crushed Digestives and Crunchies. Mix well then press it firmly into your lined tin.
Melt the milk chocolate and spread it evenly over the base in the tin. Top with chopped Crunchie pieces.
Refrigerate the whole thing for 2 hours until firm. Then just cut into slices (see notes) and enjoy!
Video
Notes
For a crack-free slice, warm up your knife. To do this, dip it into boiling water then dry it off immediately before using.
Can be stored in an airtight container in the fridge for up to 2 weeks.