Put the pecans in to the food processor and start to blend them up. At first they will turn in to small chunks, and then in to a powder. After a whilst, the powder will start to clump together and then it will slowly turn in to a butter.
This process will take around 10-15 minutes and you will need to stop it a few times to scrape the sides down and make sure it is all getting mixed up. Once the butter is nice and smooth, add the rest of the ingredients and pulse for a couple of seconds.