Wash the chicken and pat dry. Season with salt and pepper. Wash sage leaves. Put 5 pieces inside the chicken. Place the chicken on the lightly oiled fat pan of the oven.
Roast in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 1 1/4 hours. In the meantime, peel and wash the potatoes and cut them in half vertically several times. Sprinkle with salt.
After approx. 30 minutes, place on the fat pan. After approx. 40 minutes spread the fat in small flakes on the potatoes. Put parmesan and 1 sage leaf on each potato. Sprinkle chicken with remaining sage.
Clean and wash the cauliflower, divide it into large florets and possibly halve it. Cook in boiling salted water for 8-10 minutes and drain. Just before serving
For the sauce, peel the garlic, press it through a garlic press and mix with mayonnaise and yoghurt. Season to taste with salt, pepper, chopped herbs and lemon juice and let it stand for a while.
Serve everything garnished with fresh herbs and lemon.