Preheat oven to 350°. Grease a 13x9-in. baking pan., In a large bowl, combine cake mix, eggs, milk, softened butter and vanilla; beat on low speed 30 seconds. Beat on medium 2 minutes. Transfer to prepared pan. Bake 30-35 minutes or until a toothpick inserted in center comes out clean. Cool in pan on a wire rack 20 minutes. , In a 4-cup measuring cup, whisk topping ingredients until blended. Using a skewer, generously poke holes in top of warm cake. Pour milk mixture slowly over cake, filling holes. Cool 30 minutes longer. Refrigerate, covered, at least 4 hours or overnight., In a bowl, beat cream until it begins to thicken. Add confectioners' sugar and vanilla; beat until soft peaks form. Spread over cake.