Healthy Makeover: Strawberry Shortcakes

Name: Healthy Makeover: Strawberry Shortcakes
Ingredients: 3/4 cup(s) old-fashioned oats; 1.25 cup(s) all-purpose flour; 1.5 teaspoon(s) baking powder; 1/2 teaspoon(s) baking soda; 1/4 teaspoon(s) salt; 7 tablespoon(s) sugar, divided; 1/2 teaspoon(s) sugar, for shortcake tops; 2 tablespoon(s) cold margarine or butter, cut up; 3/4 cup(s) low-fat buttermilk; 2 large egg whites; 2 pound(s) strawberries, hulled, cut in half; 1/4 teaspoon(s) freshly grated lemon peel; 1 cup(s) plain fat-free Greek yogurt; 1/2 cup(s) reduced-fat sour cream; 1 teaspoon(s) vanilla extract