Position a rack in the middle of the oven and preheat to 450°F. Line a sheet pan with parchment paper.
Bring a large pot of heavily salted water to a boil. Add the cauliflower head, florets down, and cover the pot. Cook for 5-7 minutes (depending on the size of your cauliflower). Remove from water and drain on paper towels, florets facing up. Let cool for 10 minutes.
Meanwhile, place ghee in a medium bowl and microwave for 15 seconds to melt. Add curry powder, garlic powder, cayenne, and ¾ teaspoon Kosher salt (double this amount if doubling the recipe) and stir to combine.
Transfer cauliflower to parchment lined sheet pan. Flip upside down and pour a third of the curry mixture into the cauliflower from under the florets, brushing or rubbing the stem and the bottom of the cauliflower with the curry mixture. Flip cauliflower over again so the florets are facing up. Pour the remaining curry mixture on top of the cauliflower and brush or rub all over, covering all sides.
Roast in the oven until golden brown and crispy on the outside, 35-45 minutes.
Spread the tahini labneh onto a serving platter. Place the roasted head of cauliflower onto the labneh and top with the olive pine nut gremolata. Drizzle with extra-virgin olive oil and sprinkle with flaky sea salt and freshly ground black pepper, if desired.