That depends on the method you use. The main challenge is that you want to make sure that the inside is cooked through before the outside is burned. My Dad boils the cauliflower first for 10 minutes, then roasts it at 350°F for 45-60 minutes, depending on its size. But I'm lazy. The thought of a two-step recipe (and an extra pot to wash!) seemed daunting. So I decided to simply bake the cauliflower in the oven, skipping the boiling part. To ensure that the inside becomes tender, I poured a little water into the pan. This ensures that the outside gets nice and crispy, while the steam from the water penetrates the inside of the cauliflower, helping it to soften. Using my method, it takes about 80 minutes to cook the cauliflower in a 350°F oven.