Dissolve the sugar in water on a low flame. Sieve icing sugar and cocoa powder together and add this to the sugar solution. Stir continuously. Remove from fire, when the consistency of the solution becomes sticky. Add butter to it and beat well. Keep aside.
Fold into the chocolate solution, milk powder, essence and condensed milk beaten together. Add baking powder and beat again.
Spread some walnuts or cashew nuts in a greased vessel. Pour the chocolate mixture over this. The nuts can be added occasionally while pouring the chocolate mixture. When it is set, cut into desired shapes.