Remove the label from the film. Prick frying foil several times. Cook the foil in a preheated oven (electric range: 175 °C/ gas: level 2) for approx. 45 minutes. In the meantime clean, wash and halve the Brussels sprouts.
Cook in boiling salted water for 18-20 minutes. Pour onto a sieve and drain. In the meantime, wash apples, quarter them, remove seeds and cut into slices. Wash the thyme, dab dry and pluck the leaves from the stalks.
Peel and finely chop the onion. Heat the oil in a large pan, fry the onions in it until transparent. Add apple slices and thyme and fry for about 2 minutes while turning. Add Brussels sprouts and braise over medium heat for another 5 minutes.
Meanwhile bring 1/2 litre of water and salt to the boil. Remove the pot from the heat and add milk and cream. Stir in puree flakes with a whisk. Stir in butter and season puree with nutmeg.
Let the puree swell for 1 minute and stir again. Remove the cooking foil from the oven. Remove ribs from the foil. Arrange ribs, vegetables and puree sprinkled with nutmeg on a plate. Serve garnished with parsley if desired.