Place greens in a food processor, and process until finely chopped.
Melt the butter in a medium saucepan over medium heat. Add onion and garlic; cook 6 minutes or until onion is soft, stirring frequently. Add flour, salt, hot sauce, and pepper; cook 1 minute, stirring constantly. Gradually add milk, and cook until thick and bubbly (about 4 minutes), stirring constantly with a whisk.
Place egg yolks in a small bowl. Gradually add 1/2 cup hot milk mixture to egg yolks, stirring constantly with a whisk. Add yolk mixture to pan; cook over medium-low heat 1 minute. Stir in greens and 3 tablespoons cheese. Pour into a large bowl, and cool slightly.
Preheat oven to 400°.
Place egg whites and cream of tartar in a medium bowl; beat with mixer at high speed until stiff peaks form. Gently stir one-fourth of egg whites into greens mixture; gently fold in remaining egg whites. Coat a 1 1/2-quart soufflé dish with cooking spray; sprinkle with breadcrumbs. Spoon egg mixture into prepared dish; sprinkle with 1 tablespoon cheese.
Place dish in oven. Reduce oven temperature to 375° (do not remove soufflé from oven). Bake for 40 minutes or until puffy and set. Serve immediately.