From J.L. Hudson's 1945 Recipe Cards:
Phaed
J L Hudson's Mushroom Soufflé 3/4 lb mushrooms 1/4 cup minced celery * 1 cup heavy cream sauce ** 3 beaten egg yolks 3 egg whites salt paprika nutmeg Sauté mushrooms in butter, chop. Stew the celery*, drain, reserve the water*. To hot cream sauce add mushrooms and celery, reduce heat, stir in beaten egg yolks, cook until slightly thickened. Season. Cool. Fold in lightly the beaten egg whites. Bake soufflé in ungreased pan in moderate oven 325 degrees until firm - about 30 minutes. * No idea about stewing minced celery. Just cook it in a little water? ** No recipe for heavy cream sauce was included with this.