Cover the veal with cold water to "blanch". Drain and rinse the veal.

Boil about 2 cups of water in a saucepan and then add the pearl onions briefly to scald them. Drain and slip skins from the pearl onions and set aside.

In a large saucepot, combine the veal with the stock and simmer covered over medium-low heat until the veal is tender, about 1 1/2 hours. After the veal has been simmering about 30 minutes, add the sachet d'epices. Then uncover the pot to allow the stock to reduce to intensify the flavor.

Melt 4 tablespoons of the butter in a small pot and gradually add the flour to make a white roux. (Do not allow the roux to brown.) Remove and discard the sachet from the stew. Add the roux to the stew pot and simmer until thickened.

In another pan, heat the remaining 2 tablespoons of butter and gently cook the pearl onions and mushrooms until they are tender. To this pan, add the lemon juice and salt and pepper, to taste, and set aside.

The heat under the blanquette (stew) must be such that the stew is just below a boil. In a small pot, whisk together the egg yolks and cream (known as a liaison) and temper by heating gently and gradually. (You are only heating it. Do not boil. Do not cook.) Add the liaison to the blanquette. Add the reserved pearl onions and mushrooms. Adjust salt and pepper, to taste, if needed.