Preheat oven to 335˚F. Using an electric mixer combine dry ingredients for cake. In another bowl combine egg whites, 3/4 cup buttermilk, 1/4 cup oil, and vanilla.
Using mixer add butter to flour mixture until crumbly mixture forms. Combine remaining buttermilk with oil. Add oil mixture to flour mixture and mix for 2 full minutes.
Add egg white mixture to batter in 3 lots, mixing well between each addition.
Pour batter into greased and lined 8” cake pans. Bake for 35-40 minutes or until knife inserted in center comes out clean. Tap cake pans onto cutting board as soon as they are out of the oven to help even out the cakes. Allow to cool for 10 minutes before running knife along edges and removing from pans. Allow to cool for at least 30 minutes in refrigerator before frosting.
FOR THE FROSTING AND ASSEMBLY:
Add flour and sugar to small saucepan. Whisk together and cook over medium heat for 2 minutes to cook flour.
Add milk and raise heat to medium-high. Cook for 2 minutes or until thickened like pudding. Remove from heat and allow to cool completely.
Use clean electric mixer to cream butter for 1 minute. Add 1 spoonful of milk mixture at time, blending between each addition. Add remaining ingredients. Whip until smooth and creamy.
Cut tops off cakes if they are uneven. Place one on serving dish. Spread a layer of frosting on top. Place other cake on top. Spread a thin layer of frosting all over cakes to seal the crumbs in. Then use remaining frosting to frost top and sides of cake.
Cut into slices to serve and garnish with sprinkles, white chocolate shavings, or berries if desired.
