Step 2: Preheat the oven The first thing that you need to do in preparing your sponge cake is to set your oven to 180C, 350F or gas mark 4. Step 3: Mix the egg yolks Place the egg yolks into the mixer and mix them on a high speed until creamy. After a minute, add about 2 tbsp of sugar. Continue to mix for a few minutes more until the mixture becomes thicker. You can now add the vanilla extract. Keep mixing until the mixture becomes double that of its original volume. Now turn off the machine and transfer the egg yolks to a separate bowl. Wash your mixing bowl and the attachment well in preparation for whipping the egg whites. Step 4: TIP! Make sure that the mixer attachment and bowl are washed extremely clean at this point. If not, any fat that remains on these utensils will affect the whipping of the egg whites. Make sure your things are spotless! Step 5: Whip the egg whites Place whites into the clean mixer bowl. Beat them on high and let them whip until they become white and frothy. Now slowly add the sugar a bit at a time. The whipped egg whites mixture is ready when it clings to the beater attachment but does not drip. Once the mixture is nice and stiff, turn off the mixer. Step 6: Combine yolks and whites Now you can introduce the egg yolks to the egg whites mixture. Add the whipped