Preheat oven to 425°F (220°C) and line a baking sheet with parchment paper.
Cut cauliflower into medium florets and place in a large bowl.
Add olive oil, cumin, smoked paprika, coriander, cinnamon, turmeric, garlic powder, salt, pepper, and optional cayenne. Toss until evenly coated.
Spread cauliflower in a single layer on the baking sheet (do not overcrowd).
Roast for 25–30 minutes, flipping halfway through, until browned and crisp on the edges.
In a bowl, whisk tahini, honey, lemon juice, garlic, and a pinch of salt.
Add warm water 1 tablespoon at a time until smooth and drizzle-friendly.
Plate roasted cauliflower and drizzle with tahini-honey sauce. Serve warm.