Place the milk, cornstarch and vanilla in a saucepan. Mix with a whisk and bring to a boil. Meanwhile, combine the egg yolks and sugar in a bowl and whisk for 1 to 2 minutes until the mixture is light, fluffy and pale yellow. Pour the boiling milk all at once directly on top of the yolks whisking to combine well. The hot milk will cook the egg yolks. Cover with plastic wrap and let cool. When cold, add the rum.
2. Whisk about one-third of the mixture into the chocolate. Pour the chocolate mixture back onto the beaten egg whites.
3. Carefully fold the chocolate mixture into the egg whites, then pour into the souffle mold. It should reach the rim of the mold. At this point, the souffle can be kept for a good hour, refrigerated or at room temperature.
4. Place on a cookie sheet in a preheated 375-degree oven and cook for 18-20 minutes. The souffle should be moist in the center. Sprinkle with powdered sugar and serve immediately with the rum sauce around.
5. You can leave the souffle to deflate and cool overnight and then unmold it, cut into wedges and serve with sweetened whipped cream or with the rum sauce. It will have the consistency of a very light cake.
Reprinted with Permission from Jacque Pepin's Complete Techniques, ( Black Dog & Levanthal, 2001).
Andrea Reusing is the creator of the restaurant Lantern in Chapel Hill, N.C., and author of the book Cooking in the Moment: A Year of Seasonal Recipes. In this installment of The Key 3, she shares with Lynne Rossetto Kasper the techniques behind three of her favorite recipes: Turnip Soup, Overnight Braised Short Ribs and Tomato Salad.