Heat the clarified butter in a frying pan. Fry the meat in batches for approx. 3 mins., then remove from the pan. Heat a little clarified butter in the same pan. Sauté the onion and garlic for approx. 3 mins. Add the mushrooms and cook for approx. 10 mins. Pour in the white wine and reduce almost completely. Return the meat to the pan, season, mix in the parsley.
Heat the butter in a pan. Add the flour and cook, stirring with a whisk; the flour must not take on any colour. Remove the pan from the heat. Pour in the milk, bring to the boil while stirring, reduce the heat, season, simmer for approx. 10 mins., stirring occasionally until the sauce is thick and creamy. Stir in the cheese.
Spread 4 tbsp of béchamel sauce over the bottom of the prepared baking dish. Layer the lasagne sheets, filling and béchamel sauce in the dish, top with the cheese.
Approx. 35 mins. in the centre of an oven preheated to 200°C. Remove from the oven and leave to stand for approx. 5 mins. before serving.