Keep aside 1/4 cup milk & pour rest of the milk in thick bottom pan, bring it to boil, add sugar too.
While it comes to boil, prepare slurry. Add cocoa powder & custard powder in 1/4th cup milk, mix & prepare lumpfree slurry.
Once the milk starts boiling, slow down flame, add slurry, stirring continuously so it mix well with milk & no lumps are formed.
Once everything Incorporated well, again increase flame & boil for few minutes, till consistency becomes thick.
Then turn off the flame & stir it occasionally. Once it comes to room temperature, keep it in refrigerator for at least 4-5 hours so it becomes chilled.
At the time of serving, pour it in glass & top up with lots of grated chocolate. Can use corn flour instead of custard powder.
