fool-proof sponge cake

I don't remember where I got this recipe from, I just remember that I've been using it for probably 40 or more years.

SPONGE CAKE

• 4 eggs, separated
• 2 teaspoons baking powder
• 2 ounces cornflour
• 2 ounces plain flour
• 4 ounces caster sugar
• few drops angostura bitters (I often don't bother with this) 

1. Set oven at 200 degrees
2. lightly grease and flour your chosen cake tin (I mostly use an 8inch round by 3 inches high, but have used a swiss roll tin when using this for lamingtons; have also used a loaf tin and made a lamington log)
3. Sift flours and baking powder together.
4. Beat egg whites until stiff, gradually add sugar, beat until sugar is dissolved. (I use a hand mixer)
5. Beat in egg yolks. At this point add the angostura bitters if you're using them.
6. Gradually beat in flour mixture.
7. Pour cake mix into tin and bake until mixture begins to shrink from sides of tin. Top should be a pale golden brown. Takes approximately 12-15 minutes depending on type of cake tin.
8. Loosen with plastic spatula and cool the cake on a wire rack.
9. Fill and/or decorate any way you choose.

Once you get the hang of this, it's dead easy. I can make it without even getting out the recipe book. For a sponge sandwich, halve the recipe, and  make two cakes in sandwich tins. Sandwich with jam and cream, or for special birthdays, sandwich with cream and chopped strawberry jelly (jello).