On a rimmed baking sheet, toss the cauliflower with the garlic, 3 tablespoons olive oil, 2 teaspoons salt and black pepper. Spread into a single layer and roast, stirring twice, until the cauliflower is tender and the garlic is lightly browned, 20-25 minutes.
Transfer the cauliflower to a large bowl. Add the remaining olive oil, lemon juice and pine nuts, if desired. Sprinkle with 1/2 teaspoon salt, toss well and serve hot or warm.