Can I use a Food processor or does it have to be a vitamix?

I agree that you CAN use a food processor for this, but it will be a slightly rougher texture. I've made many a vegan cheese or cashew cream sauce, and the high-powered blender makes a big difference. If you're using a food processor, make sure the nuts have soaked for plenty of time, you can even actively boil them for a bit if you'd like. And add a bit of time to the grinding in the food processor. Also, if you have a smaller bowl on your processor, use that. Things like soaked cashew tend to get thrown around more in the larger bowls rather than getting truly pureed. If you only have the larger bowl, make sure to scrape down the bowl several times during the process.

You can use a food processor to blend the cashews to make these coconut vegan cheesecake bars. I see that the recipe offers that as an option in the instructions. The cashews will have been soaked a good long time, so they'll blend quite nicely. They might end up a touch grainier than when blended in a high-speed blender, but that should not stop you from using the food processor. ;o)