Begin by grinding a few saffron threads with a pinch of salt in a mortar and pestle until fine. Next, dissolve the ground saffron in rose water and let it soak for 15 to 20 minutes.

In a mixing bowl, whisk together the corn starch and ½ cup of milk until smooth. In a saucepan, heat the remaining milk and sugar over medium heat, bringing it to a gentle boil. Slowly whisk in the corn starch mixture, stirring continuously until the mixture thickens into a custard-like consistency, about 5–7 minutes. Remove from heat and let cool in an ice bath.

Once the custard base has cooled, stir in the heavy cream, saffron-rose water mixture, and vanilla extract until everything is well blended. Chill the entire mixture in the refrigerator overnight, or for at least a few hours in the ice bath.

After chilling, pour the mixture into an ice cream maker and churn according to the manufacturer's instructions, typically about 20–25 minutes. When the ice cream begins to thicken but is still soft, fold in the chopped pistachios.

Transfer the freshly churned ice cream into an airtight container, smoothing the top with a spatula. Cover the surface with a piece of parchment paper before sealing with the lid. Store in the freezer for several hours or until firm before serving.