Potato starch (sometimes called potato flour) gives this soufflé a light, airy texture. Look for it on the baking aisle. Coating the dish with breadcrumbs gives the soufflé traction to climb.
Preheat oven to 350º.
Coat a 1 1/2-quart soufflé dish with cooking spray; sprinkle with 1/3 cup dry breadcrumbs.
Combine potato starch, salt, pepper, and nutmeg in a medium saucepan, and gradually add 1 cup milk, stirring with a whisk. Bring to a boil over medium heat, stirring constantly with a whisk. Cook 1 minute or until thick, stirring constantly (mixture will be thick). Remove from heat; stir in cheese, thyme, and parsley. Spoon mixture into a large bowl, and let stand 1 minute. Whisk in egg yolk.
Place egg whites and cream of tartar in a large bowl; beat with a mixer at high speed until stiff peaks form. Gently stir one-fourth of egg whites into cheese mixture; gently fold in remaining egg whites. Gently spoon mixture into prepared dish. Bake at 350º for 35 minutes or until puffed and golden. Serve immediately.