- Soak the saffron in the hot milk for at least 30 minutes.
- Heat a heavy frying pan and toast the pistachios with 1 tablespoon of the butter for 2 minutes, until they are lightly toasted but still green.
- Remove as much skin as you can from them and set aside.
- Dissolve the sugar in the milk over low heat and keep the mixture hot.
- Melt the remaining butter in a heavy saucepan, add the semolina, and cook, stirring, over low heat for about 8 to 10 minutes.
- Stir the saffron milk into the hot sugared milk and add to the semolina, and cook, stirring vigorously.
- Remove the halwa from the fire, cover, and allow to stand in a warm spot for 15 minutes.
- Fold in the pistachios and serve warm or at room temperature in bowls.