Boil the milk. Mix cornflour with a little water to a smooth paste and add to the milk. Keep stirring till thick. Remove from heat and keep aside to cool. Stir in the sugar substitute powder and vanilla essence. Set the ice cream in an ice cream churner or in the refrigerator.

To prepare the chocolate sauce: Mix cocoa powder, drinking chocolate powder, butter and sugar substitute powder. Add a little hot water and stir till the butter dissolves. Then add some more water to make a thick sauce. Serve the ice cream topped with chocolate sauce.