In a food processor or blender, pulse the basil, Parmesan, pistachios, garlic, salt and pepper together until finely-chopped
With the food processor or blender still running, slowly drizzle in the olive oil until it is completely combined. Pause the food processor or blender and scrape down the sides, then pulse again until the mixture is smooth
Serve immediately. Or refrigerate in a sealed container for up to 3 days, or freeze for up to 3 months
