These delicate, super chocolaty souffles are sure crowd pleasers. Use the best quality chocolate you can afford. It definitely makes a difference.
5 T. unsalted butter, plus more for ramekins
1/2 cup sugar, plus more for ramekins
7 oz. semi-sweet or bittersweet chocolate, chopped (NOT unsweetened)
6 large egg yolks
1 T. vanilla extract
7 large egg whites, room temperature
pinch of salt
1/4 t. cream of tartar
Adjust an oven rack to the lower third position and preheat the oven to 400 degrees F. Butter the bottoms and sides of six 8 oz. ramekins and coat with sugar. Refrigerate until ready to use.
Melt 5 T. butter and chocolate in medium metal bowl set over a saucepan of simmering water; the bowl should be nestled in the pan but not touch the water. Stir occasionally with a heatproof rubber spatula until the chocolate and butter are melted and smooth. Whisk in the egg yolks two at a time. The chocolate may look granular at first but will become smooth like a thick fudge sauce with continual whisking. Whisk in the vanilla. Remove the bowl from over water, let cool several minutes.
In the bowl of a stand mixer, beat the eggs whites and a pinch of salt on medium speed until frothy, about 1 minute. Add cream of tartar and beat until soft peaks form Gradually beat in 1/3 cup sugar. Increase speed to medium high and beat until whites form stiff, shiny peas, 1 - 2 minutes.
Stir one-fourth of the whites into the chocolate (which may be warm) to lighten. Pile on the remaining whites and fold them n only until no white streaks remain. Divide the batter among prepared ramekins, filling to the rims. Form a "hat" in each souffle by running a thumb around the inside edge of ramekin to disengage batter from the sides. Space ramekins well apart on a large baking sheet. (Can be prepared 2 hours ahead and refrigerated or frozen up to 1 weeks and thawed 30 minutes.) Bake until the souffles are puffed and wooden skewer inserted into the canter comes out clean, but moist, 10 - 12 minutes. Serve immediately.