Blanch the Pistachios: Bring a small saucepan of water to a boil. Add the pistachios and boil for exactly 1 minute. Drain them immediately and plunge them into a bowl of ice-cold water to stop the cooking process.

Peel the Skins: Drain the cooled pistachios. The skins should now slip off easily when you pinch them between your fingers. This step is a bit fiddly but is essential for achieving a bright green colour and smooth texture. Discard the skins.

Dry and Toast the Nuts: Pat the peeled pistachios thoroughly dry with a clean tea towel. Spread them on a baking tray and toast in a preheated oven at 160°C (140°C fan) for 5-7 minutes. They shouldn't take on much colour, you just want to dry them out completely and awaken their nutty aroma. Let them cool completely.

Melt the White Chocolate: While the nuts cool, gently melt the chopped white chocolate. You can do this in a heatproof bowl set over a pan of simmering water (a bain-marie), or in the microwave in 20-second bursts, stirring in between until smooth. Set aside.

Begin Processing: Place the cooled, toasted pistachios in the bowl of a high-powered food processor. Process them on high speed. They will first turn into a coarse powder, then a thicker paste. This can take 5-8 minutes. I find that I need to stop and scrape down the sides of the bowl every 2 minutes to ensure everything is evenly blended.

Add Powders and Salt: Once you have a thick paste, add the icing sugar, milk powder, and sea salt. Continue to process for another 2-3 minutes until everything is fully incorporated and the mixture starts to become smoother and more fluid as the oils are released.

Add Oil and Chocolate: With the processor running on low, slowly stream in the neutral oil. Once the oil is mixed in, pour in the melted white chocolate.

Final Blend: Turn the processor back up to high and blend for a final 2-4 minutes, or until the pistachio cream is completely smooth, glossy, and has a flowing consistency. The heat from the processor will help everything emulsify beautifully.

Jar and Store: Pour the warm pistachio cream into a clean, sterilised jar. It will be quite liquid at this point but will thicken as it cools. Seal and store in the refrigerator.