Why You Should Cool Your Sponge Cakes Upside Down 

Chiffon Cake (yield: two 8-in round layers)
1.75 c (210g) cake flour, sifted
1.5 tsp baking powder
1/2 tsp fine salt
3/4 c (150g) sugar
1/2 c (100g) vegetable oil
6 egg yolks
1/2 c (113g) water
1.5 tsp vanilla
6 egg whites
pinch of cream of tartar
1/2 c (100g) sugar
1. Whisk together the oil, yolks, water, and vanilla in a mixing bowl.
2. Add cake flour, baking powder, salt, and first sugar and whisk to combine.
3. In the bowl of a mixer, whisk the egg whites with a pinch of cream of tartar until frothy. Add the second sugar one tablespoon at a time and continue to mix on medium-high speed until medium peaks form.
4. Gently fold the meringue into the first mixture.
5. Evenly distribute the cake batter between two 8-in cake pans that have been prepared with only a circle of parchment paper on the bottom (no grease!)
6. Bake at 350F for 30-35 minutes or until golden brown and a toothpick comes out clean.
7. Remove from the oven and let the cakes cool upside down on a sheet of parchment.
8. Once completely cool, remove the cakes from the pan.