This tender chiffon cake is ideal for layering with soaks, jams, and cream filling. It's subtly sweet, with a light-yet-sturdy texture that's airy enough to absorb flavors and strong enough to stand up to the weight of various fillings. Bake it as a sheet cake, which then gets transformed into round cake layers, like in our Princess Cake.
Preheat the oven to 375°F with a rack in the center. Line a rimmed 13” x 18” half-sheet pan with parchment. Leave it ungreased.
Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. In a medium bowl, whisk the flour, baking powder, and salt. In a large bowl, preferably one that’s wide and shallow, whisk together the brown sugar, olive oil, water, and yolks (84g) until well-combined. Sift the flour mixture into the bowl and whisk until smooth, with no lumps remaining.
In the bowl of a stand mixer fitted with the whisk attachment or working with an electric hand mixer in a large bowl, combine the egg whites (210g) and cream of tartar. Start mixing on low speed, then increase to medium-high and whisk until the whites have tripled in volume and almost reached soft peaks, 1 to 2 minutes.
With the mixer running, gradually add the granulated sugar in a slow, steady stream. Once all the sugar has been added, keep whisking until the mixture reaches stiff peaks and forms a shiny, firm meringue, about 2 minutes. Be careful not to overwhip, at which point the eggs start to break down.
Add about 1/3 of the meringue to the egg yolk mixture and whisk to combine (don’t worry about deflation — this step just lightens the mixture to make the next phase easier). Add the remaining meringue and fold it in gently with a whisk until the mixture has no obvious streaks of egg white. Switch to a flexible spatula and make sure you’ve reached all the way to the bottom of the bowl to incorporate any remaining meringue.
Gently transfer the batter to the prepared baking sheet and carefully spread it into an even layer with the spatula or an offset spatula.
Bake the chiffon cake for 18 to 20 minutes, until it’s golden brown and springs back when gently pressed.
Place a dish towel on your work surface, then remove the cake from the oven and drop the sheet pan onto your counter from about 6” high (this seems counterintuitive, but it sets the structure of the cake so that it won’t sink as it cools). Transfer the baking sheet to a wire rack to cool completely.
To remove the cooled chiffon cake from the sheet pan, run a dull knife or small offset spatula around the edge of the pan, then lay a sheet of parchment on top of the cake. Place another baking sheet of the same size, a cutting board, or a large wire rack on top of the parchment, then invert the whole set up. Peel the parchment away from the bottom of the cake; invert the cake again to make it right-side up, if desired. Finish the chiffon cake with the soak, filling, or frosting of your choice, or use it to make our Princess Cake.
Storage information: Store the chiffon cake, well-wrapped, at room temperature for 1 day. Freeze for longer storage. Defrost in the refrigerator overnight before using.
