Preheat oven to 375F. Grease and flour two 8" round pans. Combine Basic Cake Mix and milk in a large bowl. Beat at medium speed 2 minutes. Scrape bowl and beaters. Add egg whites and vanilla. Beat 2 more minutes. Pour into prepared pans. Bake 20 to 25 minutes, till a toothpick inserted in center comes out clean. Cool in pans 10 minutes, then cool on wire racks. Frost as desired.