Wash, quarter, core and finely dice the apple. Wash and dab the raisins. Mix both with 1 tablespoon lemon juice. Wash fillets, dab dry. Cut one pocket in each. Season, fill with 1-2 tbsp. apple mixture and pin.
Clean the fennel, put some tender green aside. Wash and quarter the fennel and cut into thin slices.
Heat the oil in a coated pan. Fry the fillets for 2-3 minutes on each side. Remove (put frying fat aside) and place in an ovenproof dish. Continue roasting in the preheated oven (electric range: 175°C/circulating air: 150°C/gas: level 2) for 8-10 minutes.
Steam 4 fennels covered in little boiling salted water for 6-8 minutes.
Heat the chicken frying fat. Stir in 1/4 l water, apple juice and stock. Bring to the boil and simmer for 3-4 minutes. Bind with sauce thickener, bring to the boil and season to taste.
Put the spaetzle in plenty of boiling salted water and let it simmer for about 2 minutes. Wash and chop the parsley. Drain the spaetzle and stir in the parsley. Drain the fennel, season with 1 tbsp. lemon juice, salt and pepper.
Arrange everything, garnish with fennel green.