Heat ¾ cup water in a non-stick pan, add ¼ cup sugar.
Pour milk into a bowl, add custard powder and whisk till smooth. Add it to the sugar in the pan and mix well. Cook stirring continuously, till it begins to thicken.
Add gulab jamuns and mix well. Pour into a bowl and let it cool slightly.
Pour into 4 small glass serving cups and keep in the refrigerator to chill.
Heat another non-stick pan, add 2 tbsps sugar and kala jamun pulp and mix well. Cook till well blended and slightly thick. Transfer into another bowl, cool down to room temperature and chill in the refrigerator.
Slice the kala jamuns and discard the seeds.
Take the custard cups and kala jamun pulp mixture out of the refrigerator.
Add whipped cream to the kala jamun pulp and mix well. Put it into a piping bag fitted with a star nozzle and pipe over the custard in the glass cups.
Garnish with the kala jamun slices and serve immediately.