Coat 2 (8-ounce) ramekins with cooking spray, and sprinkle with 2 teaspoons granulated sugar. Place the ramekins on a baking sheet; set aside.
Combine water and next 5 ingredients (water through egg yolk) in the top of a double boiler. Cook over simmering water until thick (about 10 minutes), stirring constantly with a whisk. Remove from heat; add vanilla.
Beat egg white and cream of tartar at high speed of a mixer until soft peaks form. Gradually add 1 tablespoon granulated sugar, beating until stiff peaks form. Gently fold one-fourth of egg white mixture into chocolate mixture; gently fold in remaining egg white mixture. Spoon evenly into prepared ramekins. Bake at 350° for 20 minutes or until puffy and set. Sprinkle each soufflé with 1 teaspoon powdered sugar. Serve immediately.