Adjust oven rack to middle position and preheat oven to 500°F (260°C). Toss cauliflower with 3 tablespoons (45ml) olive oil. Season to taste with salt and pepper. Transfer to a foil-lined rimmed baking sheet. Roast until cauliflower is tender and deeply browned on both sides, about 20 minutes total, flipping cauliflower with a thin metal spatula halfway through roasting.
While cauliflower roasts, combine remaining 3 tablespoons (45ml) olive oil, vinegar, honey, capers, pine nuts, raisins, and parsley. Season dressing to taste with salt and pepper.
Transfer cooked cauliflower to a serving plate and spoon dressing on top. Serve immediately.
