White Chocolate and Orange Soufflé

Preheat oven to 350°F. Butter 6-cup soufflé dish. Sprinkle dish with sugar; tap out excess. Heat cream and 1/4 cup sugar in heavy medium saucepan over medium heat, stirring until sugar dissolves. Add 6 ounces of chocolate and stir until chocolate dissolves. Whisk in yolks and orange peel. Cook until mixture thickens slightly, stirring constantly, about 5 minutes; do not boil. Whisk in Grand Marnier. Transfer mixture to large bowl.

Using electric mixer, beat egg whites and cream of tartar in large bowl until soft peaks form. Add 2 tablespoons sugar and beat until stiff peaks form. Mix 2 ounces chopped chocolate into warm egg yolk mixture. Fold in egg whites in 2 additions. Transfer mixture to prepared soufflé dish. Bake until soufflé is puffed and top is golden brown, about 35 minutes. Dust with powdered sugar and serve.