Our makeover halved the fat in this cake. You'll need a candy thermometer to make its Fluffy White Frosting. Candy thermometers are different from meat thermometers and can be found in many supermarkets. Store this cake loosely covered in the refrigerator.
Coat 3 (8-inch) round cake pans with cooking spray, and dust pans with 1 tablespoon flour.
Lightly spoon sifted flour into dry measuring cups; level with a knife. Combine sifted flour, baking powder, salt, and baking soda. Combine sugar, butter, and oil in a large bowl; beat at medium speed of a mixer until well-blended (about 5 minutes). Add egg whites, 1 at a time, beating well after each addition. Combine milk and yogurt. Add flour mixture to creamed mixture alternately with milk mixture, beginning and ending with flour mixture. Stir in extracts.
Pour cake batter into prepared pans. Sharply tap pans once on counter to remove air bubbles. Bake at 350° for 25 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes on wire racks; remove from pans. Cool completely on wire racks.
Place 1 cake layer on a plate; spread with half of Lemon Filling, and top with another cake layer. Spread with remaining Lemon Filling, and top with last cake layer. Spread Fluffy White Frosting over top and sides of cake.