Preheat the oven to 375 F. Slice the mushrooms. Cut the sweetbreads into 1/4-inch slices. Season the flour and toss the sweetbreads in it till lightly coated. Melt butter in a skillet, add the sweetbreads and mushrooms and fry for about 10 minutes till golden. Add the broth and seasoning and simmer for 5 minutes. Meanwhile, beat the egg with yogurt, grated cheese and seasoning. Arrange the sweetbreads and mushrooms in an ovenproof dish and pour the yogurt mixture over. Bake for 20 minutes till lightly set and golden. Sprinkle with parsley nad serve hot. Source: The Cooks Color Treasury : by Norma Mcmillian From the collection of K. Deck