Preheat your oven to 350 degrees F. Spray 3 8-inch or 4 6-inch pans with nonstick spray, line the bottoms with parchment paper and spray again. Set aside.
In a medium size bowl, combine the egg whites, whole egg, 1/4 cup of buttermilk, and vanilla.
In a bowl of an electric mixer fitted with a paddle attachment, combine the dry ingredients together on low speed for 30 seconds.
Add the butter one piece at a time, about every 10 seconds. Continue to mix on low speed until the mixture is a fine and crumbly texture. Add the 3/4 cup remaining buttermilk and mix on low speed for 5 minutes. Scrape down the sides of the bowl and begin to add the egg mixture in 3 separate batches, mixing until light and fluffy, about 4 more minutes. Scrape down the sides and bottom of the bowl to ensure all the batter has been incorporated.
Stir in the chocolate chips.
Divide batter evenly among your pans, about 16 oz of batter in each 8-inch pan or 12 oz in each 6-inch pan.
Bake the cakes until a toothpick comes out with a few crumbs inserted into the center, about 22 to 25 minutes. Let cool on wire racks for 10 minutes before inverting them onto cooling racks to cool completely.