Sift cake flour and baking powder together.
Mix eggs and sugar well, then warm them over a double boiler.
Whip egg whites until foamy.
Once the foam is firm, add the flour mixture and mix gently.
Add melted butter and milk, then blend well.
Pour the batter into an 8-inch round cake pan.
Bake in a preheated oven at 170°C (338°F) for 25-30 minutes.
Cool completely on a wire rack.