How to Make It
Preheat oven to 350°F. Beat sugar and butter at medium speed with a heavy-duty stand mixer until fluffy, 3 to 5 minutes. Gradually add egg whites, one-third at a time, beating well after each addition.
Sift together cake flour, baking powder, and salt; gradually add to butter mixture alternately with water, beginning and ending with flour mixture. Stir in vanilla extract. Pour batter into 3 greased (with shortening) and floured 9-inch round cake pans.
Bake in preheated oven until a wooden pick inserted in center comes out clean, 19 to 21 minutes. Cool in pans on wire racks 10 minutes; remove from pans to wire racks, and cool completely, about 30 minutes.
Beat cream cheese and salted butter with an electric mixer on medium speed until smooth. Gradually add powdered sugar, whole milk, vanilla extract, and salt, and beat until smooth. Increase speed to medium-high, and beat until light and fluffy.
Spread Cream Cheese Buttercream between layers and on top and sides of cake. To Pipe Frosting Petals: Spoon the frosting into a piping bag fitted with a 1/2-inch round tip. Pipe a column of 5 (1-inch) dots of frosting down the side of the frosted cake. (The dots should touch.) Place a 1-inch-wide spatula on the center of the first dot. Drag frosting outward, making a petal-like shape. Repeat with remaining 4 dots, wiping spatula clean after each use. Pipe a second column of dots on top of the swiped edges, and drag the frosting outward. Repeat, covering the entire cake, ending with 1 column of dots.
Top the cake with Cake Ball Ornaments.