Cut each chicken into 8 pieces. In a large frying pan, melt 6 tablespoons butter. Cook the chicken pieces without browning them. As they cook, remove them and put aside. In the same frying pan, put the shallots and cook for 2 minutes. Replace the chicken pieces and flambÄ with Cognac. Add the white wine, salt and pepper. Cover and cook over a low heat for 30 to 40 minutes. When the chicken pieces are cooked, remove them and keep warm. Add the garlic and parsley to the pan and reduce the sauce to about 3/4 cup. Blend the egg yolks with the crÅme fraöche. Off the heat, stir this mixture into the sauce. Replace over low heat and heat without boiling. Stir and add the tarragon and lemon juice. Off the heat add 4 tablespoons butter. To serve, surround the chicken pieces with the cooked mushrooms and onions and coat with the sauce. Serve immediately.
