Preheat oven to 375°.
Coat a 1 1/2-quart soufflé dish with cooking spray; sprinkle with 1 tablespoon granulated sugar. Set dish aside.
Combine milk, 1/4 cup granulated sugar, cornstarch, instant coffee granules, and salt in a small saucepan, stirring constantly with a whisk until blended. Bring to a boil over medium heat; cook 1 minute or until thick, stirring constantly. Remove from heat.
Gradually add hot milk mixture to egg yolk, stirring constantly with a whisk. Return milk mixture to pan. Cook over medium heat until thick (about 2 minutes), stirring constantly. Remove from heat. Add vanilla and chocolate, stirring until chocolate melts.
Place egg whites in a large bowl; beat with a mixer at high speed until soft peaks form. Gradually add 3 tablespoons brown sugar, 1 tablespoon at a time, beating until stiff peaks form.
Gently stir one-fourth of egg white mixture into chocolate mixture; gently fold in remaining egg white mixture. Spoon into the prepared soufflé dish.
Bake at 375° for 25 minutes or until puffy and set. Serve immediately topped with ice cream.