Preheat your oven to 400°F (200°C). Spread the unsalted shelled pistachios in a single layer on a baking sheet. Roast them for about 6 minutes, or until fragrant and lightly golden. Allow them to cool slightly.

In a food processor, add the roasted pistachios and blend them for 2-3 minutes, starting at a low speed and gradually increasing. Scrape down the sides as needed to achieve a coarse paste.

Add the white chocolate chips, sugar, salt, and water to the food processor and blend on high speed until smooth, scraping down the sides occasionally. This will take about 2-3 minutes.

If the spread isn't creamy enough, drizzle in a bit of neutral oil while blending until silky smooth. Check consistency as you go.

Transfer to an airtight container, seal it, and refrigerate. Let it sit a few moments at room temperature before serving.