I had tried baking sponge cake with different type of recipes about two years now and I finally found this recipe is the best.I used my Baking course step by step method to make it.I've never fail baking it using this recipe.
The cake won't sink at all .When baking cakes, it is important to remember that the ingredients should be measured very carefully- too much or too little of ingredients such as the egg,flour, oil, and sugar, can ruin the cake and its texture.Always follow the proper instructions in the recipe.The egg yolks are beaten with the sugar first while the whites are beaten separately, to be mixed in later. The mixture is then poured into the cake tin and baked. As can be seen, both methods take great care to incorporate air in the beating, whisking and sieving stages. This makes a very light product, but if you over beat the egg whites or not stiff enough,the cake will sink . 
Recipe
Ingredients
5 Eggs(Large)
70 gm Castor Sugar
80 gm Cake flour
40ml Canola Oil/Vegetable Oil
30ml Milk/water
Method
(1)Beat the eggs and sugar till light and fluffy(Double in volume)About15minutes or more
(Make sure the mixture is in white colour and stiff peak)
(2)Slowly mix the flour into the mixture using the spatula.
(3)Gradually add in oil and mix well.
(4)Bake for 35-40 minutes at 360'F.
Notes:Another method of beating the eggs is place the bowl in a smaller saucepan containing hot water,over low heat.Beat the mixture continuously as it warms.
Once the mixture started get warm and double in volume,remove from heat and beat at high speed for about 15 minutes or until the mixture cools and is very fluffy and stiff.The mixture will be triple in volume and have the consistency of whipped cream.This method is much more faster to get the volume.
Recipe
