Chiffon Cake:
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 first mixture.
5. Evenly distribute the cake batter between two 6-in cake pans that have been prepared with only a circle of parchment paper on the bottom (no grease!)
6. Bake at 350F for 25-30min 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.
Vanilla Pastry Cream:
1. Heat the milk, first sugar, and salt on medium heat until it comes to just below a boil.
2. Mix together the egg yolks, cornstarch, and second sugar in a separate bowl.
3. Temper the hot milk into the egg yolk mixture by slowly adding some of the hot liquid to the yolks while whisking constantly.
4. Return everything to the pot and cook on medium heat until thickened.
5. Off the heat, strain through a sieve and add butter and vanilla, whisking until homogenous. 6. Press plastic wrap directly on the pastry cream and refrigerate until cool.
7. Stir with spatula to loosen when ready to use.
Dark Chocolate Ganache:
1. Heat the heavy cream over medium heat until it comes to just below a boil.
2. Add the hot cream to the dark chocolate and let sit for two minutes.
3. Use a rubber spatula to stir everything together. Start by slowly mixing in the center and work your way out
Assembly
1. Run a paring knife around the edge of the cake pans and remove the cakes. Once cool, cut the cakes in half.
2. Stack the cake layers, alternating with roughly one third of the pastry cream.
3. Use a little pastry cream to smooth the edges and seal the crumbs on the top and sides of the cake.
4. After the ganache has cooled and thickened slightly, pour on top and and swirl, letting some of the ganache drip down the sides of the cake.
