Wash the chicken, dab dry and season inside with salt and pepper. Tie wings and legs together. Peel onions and garlic. Halve the onions. Cut onions and garlic into slices.
Wash, clean and quarter the tomatoes. Heat oil in a casserole. Brown the chicken on all sides and take it out. Put onions and garlic into the pot and fry until transparent. Add tomato paste and tomatoes and fry briefly.
Season with salt and pepper. Place the chicken on the tomatoes and cook in the preheated oven (electric cooker: 175 °C/ gas: level 2) for about 1 1/4 hour. Wash the basil and dab dry. Put 2 sprigs aside.
Cut the rest into strips. Add the basil and olives 10 minutes before the end of the cooking time. Cook gnocchi in boiling salted water for 1-2 minutes and quench. Heat butter in a pan and warm gnocchi in it.
Slice the parmesan and sprinkle over the gnocchi. Serve chicken with gnocchi and tomato vegetables. Garnish with remaining basil.