Boil milk and sugar. Mix custard powder, cocoa with evaporated milk and add in boiling milk. Let it boil keep on stirring to avoid lumps, till it thickens. Remove from flame and cover with lid. Crush digestive biscuits to crumbs. Place 6-7 dessert glasses on wrking table put 2 tbsp of biscuit crumbs in each glass. Pour 2 tbsp of choc custard. Repeat once or 2 more times. Top up with choc shavings or chopped kitkat. Chill in fridge