Spread the pistachios onto a baking sheet and roast in the preheated oven at 180°C for 5 minutes.
Place all the other ingredients in a pan over medium heat and bring to the boil, stirring continuously.
Add the roasted pistachios and cook until all the liquid has been absorbed.
Transfer the pistachios onto a baking sheet lined with parchment paper and roast for another 5 minutes.
Leave to cool before transferring onto a serving dish.