Preheat oven to 325º. Coat a 1 1/2-quart soufflé dish with cooking spray; sprinkle with breadcrumbs.
Heat a large nonstick skillet coated with cooking spray. Place over medium-high heat. Add corn and green onions; sauté 5 minutes or until tender. Remove from heat, and stir in ham; set aside.
Lightly spoon flour into a dry measuring cup; level with a knife. Place flour in a small saucepan. Gradually add milk, stirring with a wire whisk until blended. Cook over medium heat 3 minutes or until thickened, stirring constantly. Remove from heat; stir in cheese and pepper.
Beat egg yolks in a medium bowl with mixer at high speed until thick and pale (about 5 minutes). Gradually add hot milk mixture to egg yolks, stirring constantly. Stir in corn mixture; set aside.
Beat egg whites (at room temperature) and cream of tartar in a large bowl with mixer at high speed until stiff peaks form. Gently stir one-fourth of egg white mixture into corn mixture. Gently fold in remaining egg white mixture.
Pour mixture into prepared soufflé dish. Bake at 325º for 1 hour or until puffed and golden. Serve immediately.