this cake is traditionally baked in a tube pan but also works beautifully baked into layers for a layer cake. This is enough batter for three 8-inch round pans or two 9-inch round pans.
Prep: Preheat the oven to 350 F (177 C). Prepare your pan(s). If you are using a tube pan grease only the bottom of the pan and not the sides or the tube. If using traditional round tins, line the bottom with parchment and grease the bottom and sides of the pans. Measure out all of your ingredients for each section of the recipe and keep each grouping together to help with the flow of the recipe.
Mix the Dry Ingredients: Sift the cake flour, baking soda, baking powder, salt, and sugar into a large bowl and then whisk together to combine. Set aside.
Mix the Wet Ingredients: In a separate medium bowl, whisk together the melted butter, oil, buttermilk, vanilla extract, and egg yolks and set aside.
Make the Meringue: In the bowl of a stand mixer fit with the whisk attachment or with a hand mixer, beat the egg whites on medium/high speed until they start forming medium peaks. With the mixer still running, slowly stream in the sugar and keep beating until you reach stiff peaks.
Combine the Components: Pour the wet ingredients into the dry ingredient bowl and stir together with a rubber spatula. Once the dry ingredients are saturated, add about 1/2 cup of the egg whites into the mixture and stir it in completely to lighten the batter. Next add in 1/2 of the rest of the egg whites and gently fold them in being careful not to deflate them. Add in the rest of the egg whites and fold them in gently until completely combined. Pour the batter into the prepared pan.
Bake at 350 F (177 C) for 38-45 minutes if baking in a tube pan or 20-24 minutes if baking in layers. To check if the cake is done, gently press in on it and if it is firm but springs back it is done.
Cool & Serve: Set the cake pan on a cooling rack and allow it to cool completely before turning it out of the pan. Serve plain, dusted with powdered sugar, with a powdered sugar glaze, or frosted as a layer cake!
Store cooled cake covered at room temperature for up to 4 days.