Soak the saffron in the rose water and set aside for the saffron to release its color.

In a bowl, dilute the sahlab in a cup of cold milk; keep mixing until it has an even consistency.

Meanwhile, crush the mastic with a teaspoon of sugar and set aside.

Dissolve the rest of the sugar with the remaining 3 cups of milk and cook over medium heat.

When the milk starts to boil, add in the sahlab-milk mixture and the crushed mastic. Continue to cook over medium heat while stirring instantly.

When the mixture is thick and somehow elastic, remove from heat. Add in the rosewater-saffron mix and stir. Transfer the mix into a bowl, let cool and then put in the freezer for 2 hours.

When the mixture is frozen, transfer to an ice cream machine (or food processor) and process.

Spread the whipping cream in a tray and freeze until a crust is formed.

When you take the tray out from the freezer, leave for a couple of minutes then divide the whipping cream crust into small pieces. Mix the pieces of crust with the processed ice cream then refreeze.

To serve, sprinkle each portion with sliced pistachios.