Chocolate Soufflé

Direction :

Preheat oven and prepare baking dish:
Preheat oven to 350°F. Lightly butter a 1 1/2-quart tall-sided baking dish. Coat with sugar, tapping out excess. Set dish on a rimmed baking sheet.
Melt chocolate mixture:
In a large heatproof bowl set over a pot of simmering water, combine chocolate, vanilla, and 1/4 cup water.
Stir and cool:
Stir until chocolate is melted and mixture is smooth, about 10 minutes. Remove from heat and let cool to room temperature, 20 minutes.
Add egg yolks to chocolate mixture:
Stir egg yolks into cooled chocolate mixture until well combined. Set soufflé base aside.
Beat egg whites with sugar:
In a large bowl, using an electric mixer, beat egg whites and cream of tartar on medium-high until soft peaks form, about 2 minutes.
Add sugar and beat:
Gradually add sugar and beat until stiff, glossy peaks form, about 5 minutes (do not overbeat).
Fold in egg whites:
In two additions, fold egg-white mixture into soufflé base: With a rubber spatula, gently cut down through center and lift up some base from bottom of bowl. Turning bowl, steadily continue to cut down and lift up base until just combined.
Bake soufflé and serve:
Transfer mixture to dish, taking care not to get batter on top edge of dish; smooth top. Bake soufflé until puffed and set, 30 to 35 minutes. (Do not open oven during first 25 minutes of baking.) Serve immediately.