Preheat your oven to 350°F (175°C). Grease and flour a cake pan.

In a bowl, cream together the butter and sugar until light and fluffy.

Add in the egg yolks one at a time, beating well after each addition. Stir in the vanilla extract.

In another bowl, combine the flour and baking powder. Add to the creamed mixture alternately with the milk, mixing well.

In a separate bowl, beat the egg whites until stiff peaks form. Gently fold the egg whites into the batter until no white streaks remain.

Pour the batter into the prepared cake pan and smooth the top.

Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean.

Let cool, then remove from the pan and serve.