Set your oven to 450⁰F/220⁰C, combination steam. If your oven has variable steam settings, use 30% steam. If not, don't worry! Just set to combi steam at the correct temperature and the oven will work out the humidity for you.
If you’re doing the browned butter, put the butter in a large shallow cooking tray and put it in the oven for 2-3 minutes, until it melts and the solids begin turning brown (watch it closely, the line between browned and blackened is a fine one!).
Add the onion, mushrooms and pancetta to the tray, give it a quick stir to coat everything in the butter and return to the oven for 15 minutes, stirring after 10 minutes so it cooks evenly. There should be a little mushroom-y liquid left in the tray but if it looks soupy give it another few minutes.
Remove the vegetables and pancetta from the tray (for minimal dishes use, I just scrape it all into a bowl over the top of the zucchini, which I slice while the other things cook). You can do all of the above up to a day before you make the risotto if you like, just cover and store in the fridge until you’re ready to use it.
Change your oven temperature to 212⁰F/100⁰C, steam setting (100% humidity). If you're going straight from a hot oven for the vegetables, I'd recommend turning the whole thing off and leaving the door open for 5 minutes, then choosing the steam setting once it's cooled a bit.
Put the rice, stock and wine into the same tray you cooked the vegetables/pancetta in and season well with pepper. Steam for 17 minutes then add the veg/pancetta and the zucchini and return to the oven for a further 4-5 minutes, until the rice is tender but with a little bite in the centre.
Stir in the cheese and a little more stock or water if the risotto is too dry, then let it sit for 1 minute before serving with extra pepper.