Preheat oven to 325 degrees; coat the bottom and sides of a 10-inch springform pan with nonstick cooking spray. Sprinkle cookie crumbs in the bottom of the pan; set aside. Position knife blade in food processor bowl; add cottage cheese and cream cheese, and process until smooth. Add 1 cup sugar, whole eggs, egg whites and vanilla; process just until smooth. Pour 3 cups into a bowl. Add cocoa and 1/4 cup sugar to remaining mixture in food processor; process just until smooth. Spoon alternating mounds of cocoa mixture and plain mixture into prepared pan; swirl with a knife to marble. Bake for 60 minutes, or until almost set. Turn oven off; remove cheesecake from oven, and run a sharp knife around the edge of the cake; return to oven and let stand for 1 hour with the door ajar. Cover and chill for at least 8 hours. Spoon Dark Chocolate Sauce onto plates; top with cheesecake. (241 calories, 7.4g fat, 28% calories from fat) For Dark Chocolate Sauce: Combine cornstarch and water in a 1-quart glass measure; stir with a whisk until blended.

Add corn syrup, cocoa and sugar; stir well. Microwave, uncovered, at High for 3 minutes, or until thickened and bubbly, stirring halfway through cooking time. Stir in vanilla extract. Makes 1 cup. (per tablespoon: 38 calories, 0.2g fat, 4% calories from fat)