How much butter do you use per cup?
The site said 2tbs to 2 mugs, so I just used a tbs, but I think it could use more, thoughts?

I just made a batch of this stuff, and it is fantastic. I didn't get the fancy shmancy brand name stuff, just used some starbucks and unsalted butter. Totally unexpected, it looks like I just used cream in it, and all I did was use a counter top blender. Definitely give it a try if you haven't yet.