I actually did it. I actually went back to the store, in -35C temperatures [-47C with windchill], bought another chicken, and tried yesterday’s chicken dish again. This time, the whole bird. Head, feet and all.
The conclusion? It was not a one-off yesterday. I’m in love with this dish right now. The meat is succulent and chicken-tastic. I can’t believe I haven’t executed roast chicken like this before. How shameful. Worth noting that I gave it a good hour and a half to 2 hrs at 375F, and that I have to turn the potatoes as the sheet-pan-side gets really brown [which is good] at the exclusion of the rest of the potato quarter [which is less good].