Roast raw cashews at 350°F for 8 to 10 minutes, or use raw cashews for a milder flavor
Let the cashews cool slightly
Add cashews to a food processor or high-speed blender
Blend continuously, stopping to scrape down the sides as needed
Continue blending until the cashews go from crumbs to a thick paste to a smooth butter
Add 1 to 2 teaspoons of neutral oil only if needed for a smoother texture
Add a small pinch of salt if desired
Blend again until fully combined
Transfer to a clean jar or container
Store in the refrigerator or at room temperature in a cool, dry place