Preheat the oven to 200 degrees Celsius (392 degrees Fahrenheit), conventional oven.

Clean the Brussels sprouts by cutting off the bottoms and removing the outer leaves, so the sprouts look nice - rinse well and boil them for about 10 minutes in a small pot.

Meanwhile, divide the cauliflower into small florets and place them in an ovenproof dish.

Drain the Brussels sprouts and cut them in halves or quarters.

Add them to the dish as well.

Mix oil with lemon, salt, pepper, and crushed garlic and pour the mixture into the dish, tossing everything well together.

Sprinkle grated Parmesan on top and bake for 20 minutes in the oven.