Grease and flour an 8" cake tin. Pre-heat oven to 180°C/350°F.
Sift the dry ingredients together. Set aside.
Place the margarine in a mixing bowl, using the paddle attachment beat the margarine until it is smooth and fluffy.
Add the sugar, cream the mixture at medium speed until the mixture is also light and fluffy (about 10 minutes).
Add the egg yolks one at a time ensuring each is fully incorporated before adding the other. Mix until fluffy. Scrape down the sides of the bowl.
Combine milk and vanilla essence.
Add 1/4 of the sifted dry ingredients alternately with a third (1/3) of the liquid until all ingredients are used.
Gently fold in stiffly beaten egg whites.
Scrape batter into prepared cake tin. Bake in pre-heated oven until done.
METHOD NOTE: How to separate eggs: Crack the point of the egg gently with a metal fork, shake the egg allowing the white to drop into a bowl, while the yolk stays in the shell. Open the shell and place egg yolk in a separate bowl.
TO SERVE: For an easy dessert, slice and top with your choice of chocolate or butter scotch sauce or soft caramel custard.