In a pan, add milk and boil. Add castor sugar and custard powder and mix well, till it thickens. Now cool this mixture.
In a separate pan, add water and coffee powder and prepare a concoction.
In a separate bowl, add whipped cream and custard mixture whisk well and pipe into piping bags.
Cut a cake sponge into round shapes with a cookie cutter and place a slice at the base of a small cup. Now soak it with coffee decoction.
Now pipe the chilled custard mixture in it, and fill half the cup.
Now, repeat adding the cake slice , soak with coffee decoction , and pipe the custard mixture onto it once again filling the glass..
Let cool. Dust with cocoa powder,
Garnish with mint sprig and serve chilled.