First, place the shelled pistachios in a food processor. Blend them until they form a fine powder. Gradually add the white sugar and vanilla extract while pulsing. You want a smooth paste. If needed, add a couple of tablespoons of water for ease. Set aside.

In a saucepan, over medium heat, warm the full-fat milk. You’re looking for steam, not boiling milk. Stir occasionally to prevent the milk from scorching.

In a separate bowl, mix together the caster sugar and arrowroot powder. Once combined, slowly introduce this mixture into the warm milk, whisking vigorously. This will help prevent lumps.

Continue cooking the mixture on low heat, stirring constantly until it thickens slightly. This part should take about 5-7 minutes. You’ll notice it coats the back of a spoon.

Remove the pan from heat. Stir the pistachio paste into the warm milk mixture, blending well until fully combined.

Add the fresh lemon zest and honey. Mix well to ensure everything is distributed evenly. This will intensify the flavor profile.

Transfer it into a bowl or container. Cover and refrigerate for at least 4 hours, preferably overnight. This step is crucial for flavor development.

Once chilled, pour the mixture into an ice cream maker. Follow the manufacturer's instructions to churn it until it reaches a soft-serve consistency.

Transfer the churned gelato into a container. Freeze for a few hours to allow it to firm up to your desired consistency.