Heat the milk in a deep pan on a low flame, till it is reduced to half.
Scoop out custard apple pulp and with help of the fork or your fingers press each pod of the fruit to remove the seed. Throw away the seeds and Keep pulp aside.
Crush Almonds and add to the milk. Crush Cardamom and add to the milk.
Finally, here is the trick - Do not add jaggery in boiling milk, so switch of the flame, powder the jaggery and add. stir it well and it will dissolve.
The same trick applies to custard apple, do not boil the milk after adding custard apple. So just add the pulp, stir it few times and garnish.