This was so easy! After cleaning the sweet potatoes, I threw them in the oven at 375 degrees for 45 minutes.
I let them cool, then I slid the jackets right off with my fingers. A little messy, but simple.
Then I put them in the food mill (you don't need to use a baby one, you could use a regular one, or just mash them with a fork).
The mill is great, since it removes any bits of skin or other un-chewable matter. I got it as a shower gift from my wonderful sister-in-law, Sylvia, and I look forward to making more things with it.
As I pureed each potato, I filled recycled baby food jars with the puree and stuck them in the freezer for future use. Just make sure that you leave some space at the top of the jar or container to make room for expansion, or else you might have sweet potato oozing out into your freezer.