1. Put the meat cubes in a casserole dish with the onion studded with cloves, garlic, bouquet garni, whole peppercorns, and nutmeg. Add 2 liters of cold water. Bring to a gentle boil. Season with coarse salt, then add the carrots. Let simmer over low heat for 1 hour and 30 minutes, skimming regularly.
2. Melt 20g of butter in a frying pan and add the mushrooms.
3. Cook over medium heat for 10 minutes, turning them over. Season with salt and pepper. Set aside.
4. When the meat is cooked and tender, prepare the sauce: melt the remaining butter in a saucepan. Add the flour and cook for 2 minutes, stirring. Using a ladle, take 40cl of the cooking broth and pour it slowly into the saucepan, whisking constantly. Let cook for 2 minutes.
5. Beat the egg yolks with the cream, then pour them into the saucepan to thicken the sauce. Let simmer for 3 minutes, then keep warm in a bain-marie.
6. Using a slotted spoon, remove the pieces of meat from the broth and arrange them in a shallow dish or a large copper pot. Add the warmed carrots and mushrooms. Pour the creamy sauce over the meat and vegetables. Sprinkle with chopped parsley and serve immediately.