HEAT oven to 350°F. MIX 1/4 cup sugar, cocoa powder, flour and salt in medium saucepan; gradually WHISK IN milk until smooth. COOK over medium heat, stirring constantly until mixture thickens and boils. REMOVE from heat. STIR IN vanilla.
BEAT egg whites and cream of tartar in mixer bowl with whisk attachment on high speed until foamy. Beating constantly, ADD remaining 1/4 cup sugar, 2 Tbsp. at a time, beating after each addition until sugar is dissolved before adding the next. (RUB a bit of mixture between thumb and forefinger; it should feel completely smooth.) CONTINUE beating until whites are glossy and stand in soft peaks.
STIR egg yolks into chocolate sauce until blended. Gently but thoroughly FOLD yolk mixture into whites until no streaks of white remain. Carefully POUR into ungreased 1-1/2 to 2-qt. soufflé dish. For a “top hat”, hold metal spatula upright and make a ring on top of the soufflé mixture, 1 inch from side of dish and 1 inch deep, if desired.
BAKE in 350°F oven until soufflé is puffy, delicately browned and shakes slightly when oven rack is moved gently back and forth, 30 to 40 minutes. SERVE immediately.
Impress guests with this elegant, rich chocolate dessert. Top with raspberry sauce if desired.
For detailed soufflé techniques and information, see Basic Dessert Soufflé.
The egg white component of this soufflé, made in step 2, is actually a soft meringue. For more information, see Basic Soft Meringue.
This recipe is an excellent source of choline and protein, and a good source of folate.