Clean and joint a tender spring chicken. Put into a frying pan three tablespoons of butter and fry in this a small onion and a carrot, both cut into tiny dice. When these are lightly browned turn them into the casserole and add to them two cups of clear soup stock in which a bay leaf and a little thyme have been boiled and removed. Lay the jointed chicken in this liquid, fit the cover closely and put the casserole in the oven. It should cook for one hour with a very steady fire. At the end of this time stir in a dessertspoonful of tomato catsup, cover and cook for half an hour longer. Then add two dozen small French mushrooms, which have previously been stewed ten minutes, season, and leave uncovered long enough for the chicken to brown. The French always add a glass of sherry or some other wine to flavor their gravy.