Preheat oven to 350°F.
Combine flour, corn starch, baking soda, baking powder and salt in a small bowl; set aside.
Whisk sugar, buttermilk, eggs, egg whites, corn syrup, butter, oil, vanilla and almond extract, if desired, in a large bowl. Gradually stir in flour mixture until smooth. Pour batter into a greased 13 x 9-inch baking pan.
Bake 25 to 29 minutes until toothpick inserted in center comes out clean. Cool in pan on wire rack.
Frost cooled cake with Fluffy Cocoa Frosting or Fluffy Frosting.
NOTE: To make Buttermilk Birthday Cupcakes, follow recipe as directed, after mixing batter, divide batter evenly into 24 greased or paper-lined (2-1/2 inch) muffin cups. Bake 18 to 22 minutes, or until toothpick inserted in cupcake comes out clean.
*TIP: To make sour milk, combine 1-1/4 teaspoons lemon juice (or vinegar) with enough low fat milk to measure 1-1/3 cups. Let stand 5 minutes.