If your cake layers look like a dome on top, cut off enough to make the cake flat using a bread knife. Save the scraps for snitching or having with coffee.
Lay one cake layer on your cake plate. Spread the top and sides of the layer with the plain vanilla frosting. Distribute a layer of sprinkles over the frosting on top of the bottom layer.
Lay the second layer on top and frost the sides and top of the cake to completely cover the cake with your crumb coat. Refrigerate for 30 minutes or so. Can refrigerate overnight and continue with the frosting the next day.
Now it’s time to make your ombré colors on the sides of the cake. Place a bowl over top of the cake if you want the blue frosting to come up a little bit over the top of the cake. Using the small off-set spatula, frost about 1 inch or so of red frosting all around the sides of the cakes. Repeat the process with the white and blue frosting. We put a little edge of the blue frosting on the very edge of the top of the cake, too, for the effect we wanted.
Using your long frosting spatula dipped in a little bit of water, smooth out the sides of the cake. You will want to have the spatula right up against the sides of the cake applying a little bit of inward pressure. Refrigerate cake for another 30 minutes. Repeat the ombre frosting process with a second coat of frosting.
Gently press the sprinkles into the sides of the cake wherever you would like them.
Spread some of the white frosting over the top of the cake up to the blue edges and smooth out.
Using a small round cake decorating tip, write your message on top of the cake with either blue or red frosting. Sprinkle away over the top of the cake.
Refrigerate cake until ready to serve. Remove from the refrigerator about 30 minutes before serving.