Begin by sifting the flour at least 5 times. This will yield a very light cake. Set aside.
Beat the eggs (room temperature very important), sugar & the vanilla until pale & fluffy. It should take you some 8-10 mins.
Add the baking powder with the sifted flour & sift more 2 times or mix with a hand whisk.
Add the dry ingredients (flour + baking powder) to the beaten eggs. Beat until just mixed or fold with a rubber spatula. Be careful not to knock off the air. Do not over beat if using a beater.
Line a 17 x 11 inch cookie pan with parchment paper and grease it well with either oil or butter. Do not Over grease otherwise the cake batter will slide & not stay in place. REMEMBER : 17 X 11 pan = Super thin sponge. If it's difficult for you to handle use a 10 x 15 inch pan.
Pour the cake batter and spread evenly with a rubber spatula. It's a small amount of batter hence requires little patience to spread evenly.
Tap the pan and knock out the air bubbles.
Preheat the oven at 355 F or 180 C and bake the sponge cake in the middle rack for 8-10 mins. The time may vary according to your oven so it's advisable to check the cake at the 8 mins mark.
Do the toothpick test. Insert in the sponge, if it comes out clean that means the cake is baked right. The sponge should be springy to the touch when baked right & light golden in color.
Allow the cake to cool down a bit. When the sponge is still warm to the touch loosed its ends with the help of an off set spatula and gently pull off the parchment paper. Be very careful because its a thin sponge & very fragile.
Sprinkle the cornstarch on the top the sponge cake & roll it lightly when still warm to the touch. The cornstarch will prevent the cake from sticking .
This should be the sponge cakes first roll. It holds shape very well when rolled without the filling and kept that way for 20-30 mins.
Let's make the whipped cream now.