For the spicy cauliflower, preheat the oven to 200 °C convection. Cover a baking tray with baking paper. Clean the cauliflower and cut into 1/2 cm thick slices.
Chop the onion and garlic and place in a bowl with the cauliflower, pepper and salt, olive oil and grated Parmesan cheese and toss gently until everything is evenly distributed.
Spread the seasoned cauliflower in a flat layer on the baking sheet and place in the oven for about 25 minutes. In between, mix 1-2 times and spread out again.
Serve the spiced cauliflower as a side dish or with a herb dip as a main course.