With the electric mixer still going on a low speed, gradually add the melted butter and vanilla extract before adding the sifted flour a few spoonfuls at a time.
Gradually add the lukewarm milk and continue to beat on a low- medium speed to combine all of the ingredients.
Add the egg whites to the bowl and gently fold together the mixture.
Pour the batter into your prepared cake tin and place into your preheated oven and cook for 35 minutes or until a golden crust has formed on top of your cake.
