Adjust oven rack to lowest position and heat oven to 450°. Trim outer leaves of cauliflower and cut stem so that it is 1-inch bellow the bottom of the head. (The leaves can be saved and added to soups or stocks.) Cut head, pole to pole (down through the stem), into 8 wedges so that the florets remain attached to the stem.
Dip peeled garlic cloves into the olive oil and then wedge cloves into spaces between cauliflower florets. Using a pastry brush, brush the cauliflower wedges with olive oil all over. Place cauliflower wedges, cut-side down, on a parchment-lined baking sheet. Sprinkle with salt and pepper.
Cover tightly with foil and cook for 10 minutes. Remove foil and continue to roast until bottoms of cauliflower pieces are golden, 10 to 12 minutes. Carefully flip wedges with tongs or a spatula. Brush lightly with oil and return to the oven and continue to roast until cauliflower is golden all over, 10 to 12 minutes longer. Season with salt and pepper, as desired, and serve immediately.
If you are feeling adventurous, sprinkle a little bit of curry or chili powder over the florets after brushing with oil. Leftover cauliflower can be added to a stir-fry, pureed for soups, or chopped to serve as a baked potato topper.