Instructions
Make the Vanilla Cake
Preheat the oven to 350°F (176°C). Grease a 9×13 cake pan.
Combine the flour, baking soda, baking powder and salt in a medium sized bowl. Set aside.
Beat the butter and sugar in a large bowl on medium speed about 2 minutes, until light and fluffy. Scrape down the sides of the bowl.
Add the egg whites and vanilla and beat on medium speed until well combined and smooth.
Add about a third of the flour mixture to the batter and beat on medium speed until incorporated.
Add about half of the milk and beat on medium speed until incorporated.
Add another third of the flour mixture and beat until incorporated, scraping down the sides of the bowl as needed.
Add the remaining milk and beat on medium speed until incorporated.
Add the remaining flour mixture and beat until well combined, scraping down the sides of the bowl as needed.
Bake the cake for 35-40 minutes, or until a toothpick inserted in the center comes out clean. The cake will be browned on top.
When the cake is done, set aside to cool.
