Place a rack in the center of your oven and preheat to 425 degrees F.
Line a baking sheet with aluminum foil for easier cleanup, if desired.
Pull the leaves off of the cauliflower base. Cut off the lower part of the stem. Cut the head of cauliflower into four quarters. Slice each quarter into 6-8 pieces. You want as many flat surfaces as possible on each floret-- the flat surfaces caramelize best. Caramelization is the key to giving the roasted cauliflower flavor.
Spread the florets out in an even layer on the baking sheet. Reserve any small bits of cauliflower that have fallen away from the florets in a small bowl.
Drizzle the florets with olive oil, salt and pepper, then toss. If using parmesan or lemon juice, sprinkle those on at the end of roasting.
Place the baking sheet into the preheated oven and let the cauliflower roast for 10 minutes. Toss then return the baking sheet to the oven. Let the cauliflower roast for 10-20 minutes longer till tender and golden. When it's ready you will be able to pierce it easily with a fork.