Put the milk into a wide, heavy pan and bring to boil over high heat, stiring constantly.
Now lower the heat and cook the milk, stirring constantly, until it has thickened and reduced to about 13/4th cups. (This will take about 40-45 minutes). Stir the sides of the pan constantly to avoid scalding.
Now add the sugar, nuts and cardamom seeds, stir well, allow to cool.
Pour the mixture into Kulfi molds or small ramekins, distributing evenly. Cover with plastic wrap or foil and freeze until set, about 6 hours.
To serve, remove the ice-cream from the molds by running a sharp knife around the edges of the pista kulfi. Slip each kulfi on to a dessert plate, cut across into 3-4 slices, and serve.