Unlike most chocolate soufflés, this is made without milk or starch. It is light yet moist, with an exceptional chocolate taste.
Position a rack in the lower third of the oven. Preheat the oven to 375°F. Prepare a 7-inch or 1 ½-quart soufflé mold, above.
Combine in a medium heatproof bowl:
Set the bowl in a skillet of hot but not simmering water and stir until the mixture is smooth. Let cool for 10 minutes, then whisk in:
Beat in a large bowl on medium speed until soft peaks form:
Increase the speed to high and gradually beat in:
Beat until the peaks are stiff but not dry. Using a large silicone spatula, stir one-third of the egg whites into the chocolate mixture, then fold in the remaining whites. Pour the batter into the prepared soufflé mold and smooth the top. (The soufflé can be set aside at room temperature, covered with an inverted bowl, for up to 1 hour; or cover with plastic wrap and refrigerate for up to 24 hours before baking.)
Bake until the soufflé is risen and set, 25 to 30 minutes. Serve at once with: