I made this tonight.  Definitely a keeper.   I used two white sweet potatoes, three carrots, two parsnips, a good dozen garlic cloves (on the grounds that they were small), and added an onion cut in sixths.   I used a bit more seasoning and rubbed some on the chicken under the skin.

Next time I’d cut back on the olive oil (but I eyeballed it so the recipe may be right), try boneless thighs, and maybe skin some of the chicken to see how it comes out.