1 (2 lb.) lamb fillet
1/4 c. butter
4 shallots, chopped
1 tbsp. flour
2 c. chicken stock
3 tbsp. lemon juice
1/2 lb. button mushrooms
1 rosemary sprig, divided, or 1/2 tsp. dried
Salt & pepper
2 egg yolks
2/3 c. single cream

Cut the lamb into 1" pieces. Melt the butter in a flameproof casserole and saute the lamb with the shallots. Do not allow the meat to brown. Saute until the shallots are softened but not colored. Sprinkle the flour into the casserole and cook for 1 minute. Stir in the stock and the lemon juice. Add the mushrooms, rosemary, and seasoning. Bring to the boil, stirring continuously, cover and cook in a moderate oven, 325 degrees, for 1 hour or until the meat is tender.

Beat together the egg yolks and cream and stir in 3 tablespoons of the sauce from the casserole. Blend the mixture into the casserole and warm through over gentle heat until thickened. Do not allow to boil. Adjust seasoning if necessary. Serves 4.