04Combine egg whites with cream of tartar in a medium mixing bowl. Beat on medium speed until soft peaks form. Gradually sprinkle in remaining 1/4 cup sugar and beat on high speed until stiff but not dry.05Fold about 1/3 of the chocolate mixture into the egg whites. Fold in the remaining chocolate mixture in 2 additions. Divide batter into prepared ramekins.06Drop one 1/2 ounce of dark chocolate into the center of each souffle just before baking.07Bake for 10 to 12 minutes, or until the top has formed a nice crust and the sides appear cake-like. Sprinkle with powdered sugar. Dig in immediately!