I was going to suggest “pizza beans” or “baked” ziti or other all-in-one pasta in the slow cooker until I saw your tomato note.
I recommended milk-braised beans earlier on the NYT thread, and that might work well in the slow cooker too (especially for dried beans — soak overnight). I like it with cannelini or gigantes.
And of course the origin recipe for that is milk-braised chicken / pork, which would also work very nicely (I’d thin the milk with a bit of water).
