Divide the egg yolks from the egg whites Melt chocolate in a metal bowl set over a saucepan of barely simmering water (or a double-boiler, if you have one), stirring until the chocolate is melted and uniformly smooth.
Remove bowl from heat and stir in yolks.
Beat whites in a large bowl until they just hold soft peaks.
Add 1/3 cup sugar, a little at a time, continuing to beat, then beat at a higher speed until whites just hold stiff peaks.
Stir about 1 cup whites into chocolate mixture to lighten, then gently yet thoroughly fold mixture into remaining whites.
Transfer mixture into soufflé dish.
Bake in center of oven until it appears cooked and crusted on top but is still jiggly in center (roughly 25 minutes).