Preparation Heat oven to 350°F. Coat a 9" cake pan with cooking spray; dust with flour. Beat butter and 1/3 cup sugar in a bowl with an electric mixer until fluffy. Beat in another 1/3 cup sugar. Add buttermilk, then egg whites one at a time, beating well. In another bowl, mix flour, polenta and baking powder. Add to butter mixture along with vanilla; mix. Pour into pan; arrange apples on top. Sprinkle with remaining 1 tbsp sugar; bake 45 to 55 minutes. The skinny: 203 calories per serving, 4.9 g fat (3 g saturated), 1.2 g fiber, 38.5 g carbs, 2.8 g protein Nutritional analysis provided by Self