We don’t think that you need to par boil the cauliflower. We’ve made this recipe both with and without parboiling the cauliflower, and we got better results when we didn’t. If you don’t parboil, it means that the sauce has time to reduce down in the oven while the cauliflower cooks. You’ll end up with chunks of cauliflower that have a good bite to them, and the sauce will have a good consistency. Parboiling means you risk ‘mushy’ cauliflower, or a sauce that’s too runny.