Line a small square tin with baking parchment and dust lightly with rice flour. Keep a sugar thermometer ready and ensure all ingredients are measured before cooking, as timing is crucial once the syrup begins. Move on once your setup is organised.

In a heavy based saucepan, combine the sugar and water over medium heat. Stir gently until dissolved, then stop stirring and allow the syrup to boil until it reaches 115°C. Add the glucose syrup and continue boiling until it reaches 125°C, then remove from heat and prepare to work quickly.

While the syrup cooks, beat the egg whites in a clean bowl until stiff peaks form. The whites should hold their shape firmly without appearing dry. Once ready, keep the mixer running on low speed and move to the next step.

Slowly pour the hot syrup into the whipped egg whites in a thin stream, continuing to beat constantly. This step sets the structure of the gaz, so pour steadily and avoid splashing to maintain a smooth texture.

Increase the mixer speed slightly and add the rosewater and cardamom. Beat until the mixture thickens and turns glossy, with a marshmallow like consistency. When the mixture begins to pull away from the bowl, proceed to the next step.

Using a spatula, gently fold in the chopped pistachios until evenly distributed. Work carefully to avoid deflating the mixture, then prepare to shape while it is still warm.

Transfer the mixture into the prepared tin, smoothing the surface with a lightly oiled spatula. Dust the top with rice flour and allow it to cool at room temperature for at least 6 hours until fully set.

Once firm, remove from the tin and cut into small rectangles or diamonds using a sharp knife dusted with flour. Arrange neatly and prepare for serving.

Serve gaz with Persian tea or light coffee. Store pieces layered with parchment in an airtight container. Lightly dust with extra flour just before serving for a traditional finish.