gbck, my mom used to make potato candy for us all the time! She usually made it around Easter instead of Christmas though.
I made my girlfriend from PA's potato candy last year. Oh, my word. It was the most disgusting thing I've ever tasted. My kids agreed with me. That never happens. I'm willing to admit operator error, but as far as I could tell, I followed the recipe to the letter. Mashed potatoes? Candy? I couldn't even ask people to "try it before I tell you the secret ingredient" like I did with my bacon chocolate bar.