Preheat the oven to 335°F, then grease and line two 8-inch cake pans with parchment circles on the bottoms.

In the bowl of an electric mixer, combine the cake flour, sugar, salt, baking powder, and baking soda; in a separate bowl, stir together the egg whites, 3/4 cup of the buttermilk, 1/4 cup of the vegetable oil, and the vanilla extract.

Add the softened butter to the dry ingredients and mix until the mixture looks crumbly.

Combine the remaining 1/2 cup buttermilk with the remaining 1/4 cup vegetable oil, add it to the flour mixture, and beat for a full 2 minutes.

Add the egg white mixture in three additions, mixing well after each addition and scraping down the bowl as needed, until the batter is smooth and pale.

Divide the batter between the prepared pans and bake for 35 to 40 minutes, until a knife inserted into the center comes out clean.

As soon as the pans come out of the oven, tap them on a cutting board to help level the layers, cool in the pans for 10 minutes, run a knife around the edges, turn them out, and refrigerate the layers for at least 30 minutes before frosting.

While the cakes cool, whisk the frosting sugar and flour together in a small saucepan and cook over medium heat for 2 minutes, whisking so the flour cooks and nothing scorches.

Add the milk, raise the heat to medium-high, and cook for about 2 minutes, or until the mixture thickens like pudding, then remove it from the heat and let it cool completely.

Using a clean electric mixer, cream the room-temperature butter for 1 minute, then add the cooled milk mixture one spoonful at a time, beating between additions; add the vanilla, almond extract, and salt, and whip until smooth and creamy.

Trim domed cake layers level if needed, place one layer on a serving plate, spread frosting over the top, add the second layer, apply a thin crumb coat over the entire cake, then frost the top and sides with the remaining frosting and decorate with sprinkles, white chocolate shavings, or berries if desired.