Bloom: Crush saffron with a pinch of sugar. Stir in 2 tbsp hot water. Set aside.
Heat: Mix milk, sugar, and 1/2 cup cream in a pot. Heat until steaming.
Whisk: In a bowl, whisk yolks until pale.
Temper: Slowly whisk 1/2 cup of hot milk into the yolks, then pour the yolk mixture back into the pot.
Thicken: Stir over low heat until the custard coats a spoon (about 170°F or 77°C). Do not boil.
Flavor: Stir in saffron water, rosewater, vanilla, cardamom, and the remaining 1/2 cup cold cream.
Chill: Cool to room temp, then refrigerate for 6 hours.
Churn: Process in an ice cream maker. Add pistachios in the last few minutes. Freeze until firm.