Wash the mushrooms and cut off the caps. Reserve the stems for another dish. Cut the caps into strips about ¼ in.

Heat 1 tablespoon of butter in a skillet over medium high heat. Once the butter is melted, add the mushrooms and sauté for 3 minutes.

Fill a pan with hot water and place over high heat. Put a steamer over the top of the pot. Add the frog legs when the water begins boiling. Cover and cook until tender. Remove from the streamer and place on a baking dish.

Melt 2 tablespoons of butter.

Add the crab meat to the frog legs and pour the melted butter over the top of both. Pour sherry over the whole. Cover tightly with foil and allow to infuse for half an hour. Preheat the oven to 350 degrees F.

Place in the oven and bake for 5 minutes. Remove about half the liquid, and sprinkle the mushrooms over the frog legs. Place in a warming drawer.

In a saucepan, mix together the cornstarch and water. Add this mixture to the scalded cream, little by little until well blended. Cook for 20 minutes, stirring constantly until thickened. Blend in the egg yolk. Serve this sauce over the frog legs.