And lo and behold, I am not the only person who has ever thought of this!
Here's the recipe for anyone who is interested. You will see that it really is very easy.
Note: you have to use fresh, not frozen, breastmilk. (Is "breastmilk" one word or two?)
I won't be trying this right now since we're not starting solids just yet, but when I do, I will be sure to post the results.
I have made my own yogurt though, many times, and it really is remarkably easy.
And thanks to Jen for wishing me a happy blogaversary. Wow, one year! (Approximately.)