The oven to 350 degrees.To make the cake, combine the first five ingredients in a large bowl and whisk with a mixer on medium speed (about 5 minutes). One at a time, beat thoroughly after each addition of eggs and egg whites. Flour should be measured with a light spoon and leveled with a knife. With a whisk, thoroughly combine the flour, baking powder, salt, and baking soda. Beginning and finishing with the flour combination, alternately add buttermilk and sugar mixture to the sugar mixture; beat thoroughly after each addition.
Pour the batter into two (9-inch) round cake pans that have been sprayed with cooking spray. Firmly tap the pans against the counter to release any air bubbles. A wooden pick inserted in the center should come out clean after 20 minutes of baking at 350°. Remove from pans after cooling in pans for ten minutes on a wire rack. Complete cooling on a wire rack.
To make frosting, combine the first 4 ingredients—cream cheese through 2 tablespoons of butter—in a big bowl and beat on high speed until frothy. Just until combined, add the powdered sugar, and beat at low speed (do not overbeat). 1 hour of cooling
On a plate, place 1 cake layer, then cover with 1/2 cup frosting. Add the last layer of cake on top. Overspread the cake's top and sides with the remaining icing. Cake should be kept in the fridge with a loose cover.