They'll be climbing the castle walls to get to this royal cake.
Cut one cake into four equal pieces and arrange three of them atop the four whole cakes, as shown, securing with icing. (Tip: Cut up the extra cake piece for nibblers.)
Frost the castle and cones with the white icing, then sprinkle the cones with edible glitter and set them on the castle.
With a pastry bag, create pink icing corner pillars and a door with mini jawbreaker studs.
Set the gumdrops and Good & Plentys around the castle ledge, then add decorative loops of gel icing and the mini candy hearts.
Finally, add the sprinkles around the top of the castle and top the cone turrets with flags cut from the colored paper and taped to the toothpicks.