Roasted Cauliflower “Steaks” with Mushrooms

I don’t mean to pretend: a) that cauliflower totally resembles steak; b) you should eat cauliflower as a meat substitute, works just as well; or c) cauliflower is inherently awesomer when sliced in thick and satisfying slabs. No, no, no. But this is fun, and you should try it.