In a bowl sift together the flour, baking powder and salt, and set aside.
In another, big bowl, using a mixer, beat the butter and sugar to cream together for about 5 minutes or until the mixture starts to whiten and turns fluffy.
Beat in the egg yolks, one at a time. Then beat in the vanilla extract and the orange zest and juice.
Add in the flour mixture to the batter, little by little mixing in between, until well incorporated and set aside.
In a small bowl whisk the egg whites until light and fluffy.
Add the egg whites to the batter by carefully stiring with a rubber spatula.
Pour the batter in your desired cake pan, previously greased and floured, and bake at 350°F (180°C) for 40 minutes aprox. or until a wooden stick comes out clean when inserted.