Beat the butter and eggs together very well. Add the dry ingredients, vanilla, water, and egg whites and mix well.
Spread the batter into 2 well-greased 9-inch cake pans. Bake at 350 degrees F for 18-20 minutes or until the tops are nicely puffed up and a toothpick comes out cleanly. Remove the cakes from the oven and let them cool for 5 minutes. Run a knife around the edges of the cakes and gently remove them from the pans, transferring them to a wire rack to cool. Refrigerate overnight before frosting and serving. Yields 2 9-inch cake layers (approx. 12 servings).
Recipe by Briana Thomas at https://www.briana-thomas.com/basic-white-cake/