1. Prepare the oven by preheating it to 425F. This is usually done with the "Bake" setting.
2. Chop the cauliflower into florets of the size seen in the picture. It's ok if some are smaller than others. The best way to do this is by cutting off the large, leafy stem and then cutting up into the head of the cauliflower to remove most of the stalks.
3. Once you have your florets, place them in a medium-sized mixing bowl. Drizzle the olive oil over the top, and then use your hands to mix the florets around so they all get covered in olive oil. This should leave the florets with a light sheen of olive oil.
4. Now, spray a baking sheet lined with tin-foil with cooking spray (like PAM), and dump the bowl of florets onto the pan. Then, salt and pepper the florets as you see fit and place them in the oven for about 25 minutes.
5. Check the florets about 5 minutes before they should be done to make sure they aren't burnt. After the time is up, take the florets out and try one (after it cools down a bit) to see if they are cooked through. They should be somewhat firm but not mushy.

Great Job! Now you know how to roast cauliflower.

Cauliflower is high in fiber and several vitamins, such as vitamin C, K, anf folate. It is also fairly low in calories, at around 40 in a cup of cooked cauliflower.