Bring a medium-sized pot of water to a boil. Add the shelled pistachios and boil for 3 minutes.

Drain the pistachios and place them on a clean kitchen towel. Fold the towel over and rub gently to remove the skins. Discard the skins.

Place the cleaned pistachios into a blender.

In a small microwave-safe bowl, combine the butter and 60ml of milk. Heat in the microwave in 20-second bursts until the butter melts and the milk is hot.

Add the chopped white chocolate to the bowl. Stir until melted. If necessary, heat for an additional 10-15 seconds.

In the blender with the pistachios, add the remaining 130ml of milk, confectioner's sugar, kosher salt, and the melted white chocolate mixture.

Pulse on medium speed until the pistachios turn into a paste, stopping 3-4 times to scrape down the sides.

Blend on high power for 30 seconds to 1 minute until the mixture is smooth and creamy.

Transfer the pistachio cream to an airtight container and refrigerate until ready to use. It can be stored in the fridge for up to 2 weeks.