Whisk together olive oil, spices, salt and pepper.
Combine cauliflower and onions, then toss with oil mixture.
Spread cauliflower mixture on lined cookie sheets in a single layer.
Bake for 20 mins, turn and toss the cauliflower, then return to oven and bake for an additional 15-20 mins until cauliflower is tender and lightly browned. Remove from oven and serve.