How much of this could be made ahead of time, and how would you do it? (I'm concerned about the Brussels sprouts not holding up well.) ;o)

If you bake it for 20 minutes on a baking sheet, and watch closely, it shouldn't dry it out too much!

Thanks, Elana. Did the test kitchen bake the stuffing on a baking sheet (as opposed to in a casserole) and then just lift it in chunks into the casserole for serving? I can see how you'd get a lot of crust that way, but I'm concerned that might be just a bit too unconventional, and that the stuffing might be too dry, if cooked that way. Thank you. ;o)

Great question. You can go one of two routes in order to make this stuffing ahead.
1) Fully prepare and bake until vegetables just shy of doneness. One the day of, finish baking off.
2) Roast the vegetables separately the day before. Combine with the remainder of ingredients on the day of and bake for 20 minutes.