Haha I just found that site!
All-Natural Pumpkin Butter From Scratch + Many Ways To Use It!
I wonder if I would need to add anything to make it shelf stable after canning, or if the canning process automatically makes it safe. I know some things call for citric acid, but I don't know if that has more to do with color preservation.  Oh, it calls for lemon juice. Should be fine for canning.
 Dammit! http://nchfp.uga.edu/publications/ug...in_butter.html I guess not.