Heat milk in a saucepan and bring it to boil. Let it boil, stirring continuously, till reduced to one-third the original quantity. Add khoya and mix. Then add condensed milk and reduce for five more minutes.
Take it off the heat and add grated chocolate, leaving aside some for the garnish, and mix well.
Transfer the mixture into kulfi moulds. Sprinkle the remaining grated chocolate on top and close the lid of the moulds. Keep the moulds in the deep freezer and allow to set.
When set unmould, slice and serve immediately.