Preheat oven to 400 degrees.

Remove all the leaves from under the cauliflower. Place it in an oven safe dish.

Mix the olive oil, the ranch and salt/pepper in a bowl until smooth. With a spoon or a brush evenly coat the whole cauliflower. Turn it upside down and drizzle a bit of the mixture underneath as well. You may also discover that using your hands makes this process go faster.

Cover with foil, make sure no steam escapes. Cook in the oven for about 50 minutes, or until a skewer goes thru the cauliflower easily. It will vary on the size you have, of course.

Remove the foil, and broil for about 2 or 3 minutes. Or until it starts to brown on the top. Keep an eye on it, as it burns easily.

Allow to rest for 5 minutes before slicing. Season with extra salt if needed.