Preheat oven to 350°F. Mix cake mix, eggs, milk, oil and vanilla in large bowl with electric mixer on low speed 1 minute. Beat on medium speed 2 minutes. Pour into 2 greased and floured 9-inch round baking pans.
Bake as directed on package. Cool on wire racks.
Place 1 cake layer on serving plate. Spread with about 1/2 cup of Whipped Vanilla Buttercream Frosting. Top with remaining cake layer. Frost top and sides of cake with remaining frosting. Garnish as desired.