In a dry frying pan, toasted until fragrant:
1 tbsp cumin seeds
1 tbsp coriander seeds.
Crush the toasted spices in a mortar and pestle.
Toss the cauliflower with the oil, salt, pepper and half the ground spices before roasting. Bake at 400F for 30 to 45 minutes. Stir or flip every 15 to 20 minutes to ensure even baking.
Like it hotter? Add 1 tsp of chili flakes.