Preheat the oven to 325 degrees F. Grease and flour three 8 inch pans, adding a circle of parchment or wax paper to the bottom of each pan.
Go ahead and separate your eggs, saving only the 6 egg whites for this recipe. Set them in a bowl to the side.
In a medium bowl, whisk the flour, baking powder, baking soda, and salt for 30 seconds and set aside.
In another bowl, add the buttermilk, vegetable oil, and vanilla extract. Set aside.
In the bowl of your mixer, add the butter and cream cheese and mix at medium speed until smooth.
Gradually add the sugar and mix at medium speed for 2-3 minutes.
Mixing on low speed, add the 6 egg whites one at a time (it's fine to estimate), mixing to incorporate after each addition.
With the mixer on low speed, alternately add the flour mixture and the milk mixture, beginning and ending with the flour mixture (We did 3 additions of the dry mixture, 2 additions of wet)
Mix the batter just until well combined- be careful not to over-mix. Divide the batter between the three pans.
Bake at 325 degrees F for 28-30 minutes or until a toothpick inserted into the center comes out clean or with just a few crumbs attached. Let cool for 5-10 minutes in the pans on a wire rack before turning out. *Baking times may vary slightly.
This recipe makes 7 ½ cups of batter.