Preheat oven to 350°F. Grease and flour two 9x2-inch round cake pans.
Have all your ingredients measured and ready to go. With white cake, especially butter white cake, this is very important.
Sift the cake flour if you haven't already, then whisk it with the baking powder and salt and set aside.
Mix the extracts with the milk.
In a mixing bowl, using an electric mixer (I use a stand mixer and paddle) beat the butter and sugar until light and creamy. As always, be sure to scrape the bowl often. With the mixer on low speed, add the flour mixture and milk in three parts, alternating with the milk.
In a separate bowl, beat the egg whites until stiff peaks just start to form, but don't beat until dry.
Fold in ⅓ of the whipped egg whites to lighten the batter, then fold in the rest.
Divide cake between the two pans and bake for about 28 minutes, until inserted cake tester comes out clean. Let cool in the pans for 5 to 8 minutes. Loosen cake from pan and invert onto a wire rack to finish cooling.