Heat milk in a heavy, wide pan for 18 to 20 minutes on low flame. Stir often so that it doesn't burn at the bottom.
Dissolve rice flour or cornstarch in some milk. Mix and keep aside.
Grate or crumble khoya (mawa) on a plate. Process unsalted pistachios and almonds to a semi-fine consistency in a mortar-pestle.
Add sugar to reduced milk and mix well. Keep scraping the milk solids from the sides and adding them to the simmering milk.
After the sugar has dissolved (3 to 4 minutes), add rice flour or cornstarch paste. Keep stirring, till the milk thickens.
After the mixture has thickened, add the grated khoya, powdered nuts and cardamom powder.
Stir well and simmer on low heat for a minute or two.
Switch off heat, add rose or kewra (pandanus) water and crushed saffron. Adjust the sugar, if required.
Cool the mixture to room temperature and pour in kulfi moulds, shot glasses or serving bowls.
Cover with aluminium foil or lids and freeze overnight or till the kulfi is set.