Put the chicken, potatoes, cauliflower and onions into a roasting tin (the tin should be large enough for everything to lie in a single layer, otherwise the chicken and vegetables will sweat instead of roasting).
Add the thyme (tear it roughly and throw it in), olive oil and some seasoning. Toss all this around with your hands.
The chicken should finish with the skin-side facing up. Sprinkle a little flaked sea salt over each piece of chicken – this will help the skin to crisp.
Roast for 35 minutes, tossing occasionally – you have to ensure that the cauliflower gets golden all over, not just on one side. Sprinkle with the Parmesan, then toss to combine and roast for another 10 minutes.
The chicken and potatoes should be cooked through, the onions slightly scorched at the tips and the surface of everything golden.