Place the digestive biscuits into a large plastic bag, seal and bash up to a crumb using a rolling pin. Empty the crumbs into a large mixing bowl.
Place 200g of the milk chocolate into a glass bowl and add the butter, syrup and cocoa powder. Place over a pan of boiling water and stir until melted together.
Pour the chocolate mixture over the digestive crumbs and stir until well combined.
Line a 32cmx18cm baking tray with greaseproof paper. Tip the biscuit mixture into the tray and using the back of a metal spoon spread the mixture, taking care to even it out and press into the corners. Place in the refrigerator for 30 minutes.
Break up the remaining 200g milk chocolate into a clean bowl and place over a pan of boiling water, stir until melted. Remove the biscuit tin from the refrigerator and pour over the melted chocolate. Return to the fridge until the chocolate has solidified before removing and cutting into squares.
This recipe can be added to easily with the addition of dried fruits or some crushed up honeycomb. Simply stir through along with the biscuit.