Preheat oven to 325℉ and grease a 9x13-inch pan. See notes below if making a layered cake.
In the bowl of a stand mixer (or in a large bowl), combine the cake mix, flour, and sugar.
1 15.25-ounce box white cake mix, 1 cup flour, 1 cup sugar
Add the sour cream, milk, egg whites, melted butter, vanilla extract, and almond extract (if using).
1 cup sour cream, 1 cup milk, 4 egg whites, 1/2 cup butter, 1 teaspoon vanilla extract, 1 teaspoon almond extract
Beat for 1 minute, scraping down the sides of the bowl half-way through.
Pour into your prepared pan and spread to an even layer.
Bake for 28-32 minutes or until a toothpick poked into the middle of the cake comes out clean.
Let the cake cool completely before frosting.