Step 1

Preheat oven to 325 degrees F. Spread shelled or slivered pistachios in an even layer on a cookie sheet. Bake for 5 to 10 minutes or until fragrant but not yet browned (slivered pistachios will need less time, blanched or whole pistachios will need a few minutes more). Remove from oven and let cool slightly.

Step 2

Transfer toasted pistachios to the bowl of a food processor or blender. Process until pistachios break down in to a fine powder. If you're using a blender, get out the tamper so you can keep the nuts moving.

Step 3

Continue to blitz the nuts for 5 to 10 minutes, scraping down the sides of the bowl as you go, until smooth and creamy. If you want, a teaspoon of pistachio oil will help the butter process more smoothly.

Step 4

Once the butter has achieved your desired consistency, add a pinch of salt (if desired) and pulse once or twice more to combine. Transfer to a jar or other container with an airtight lid.

Step 5

While pistachio butter does not require refrigeration, it is recommended; refrigerated in an airtight container it will keep for about a month or so. You can also freeze it for even longer.