Clean, pare and blanch the Sweetbreads. Then cut into very small pieces and put them into a saucepan with two tablespoonfuls of butter; let them saute a moment and then add the mushrooms and truffles all cut very fine. Add a pint of Sauce Allemande, and let the mixture cook on a slow fire for six or eight minutes, tossing gently all the while. Add a teaspoonful of butter. Stir well and use for any garnishing desired.