Preheat oven to 350 degree F. Grease a 13x9x2-inch baking dish or 3-quart rectangular casserole; set aside. For batter, in a blender or food processor combine eggs, egg whites, dairy sour cream, orange peel, orange juice, and softened butter. Cover; blend or process until smooth. Add flour, sugar, and baking powder. Cover; blend or process until smooth. Transfer to a medium bowl; set aside. Rinse blender jar or food processor bowl.
For filling, in blender or food processor combine cottage cheese, cream cheese, egg yolks, sugar, and vanilla. Cover; blend or process until smooth; set aside. Pour about 2 cups of the batter into prepared dish. Spoon filling mixture over batter in dish; swirl filling into batter with a knife. Pour remaining batter evenly over mixture in dish.
Bake about 45 minutes or until puffed and lightly golden. Cool 30 minutes on a wire rack (edges may fall during cooling). Serve with Raspberry-Orange Sauce. If desired, serve with fresh raspberries, orange sections, and mint sprigs. Makes 12 to 15 servings.
Wash blender jar or food processor bowl thoroughly. Thaw frozen raspberries in syrup; do not drain. Place in blender or food processor. Cover and blend or process until smooth. Strain through a fine mesh sieve; discard seeds (should have 3/4 cup puree). Place puree in small pan. Stir in cornstarch. Cook and stir over medium heat until thickened and bubbly. Cook and stir 2 minutes more. Stir in orange juice. Serve warm or at room temperature. Makes 1 cup sauce.