Remove the red colored sorbet from the freezer.
Slice the pound cake through to make 3 equal layers. Cut each of the 3 layers in half then cut each half diagonally into triangles.
Line the bottom of a high-sided, 8- to 9-inch cake pan with enough plastic wrap to come up and over the sides. Squish the pieces of pound cake into the bottom of the pan to form an even layer (Really smash them in. It doesn’t have to be pretty; just cover the bottom completely with cake).
Spoon the red sorbet into a mixing bowl and, using a potato masher or a spoon, flatten it out in the bowl to make a disc shape. Make sure it’s not too watery—if it’s still too cold, microwave it in 5-second increments until it’s soft enough. Slide the red sorbet over the pound cake with a spatula, ensuring the layer is evenly spread out. Place in the freezer for at least 45-60 minutes.
Pour the orange/yellow sorbet in a mixing bowl and work it with the potato masher the same way you did the red sorbet. Remove the cake from the freezer and spread the orange/yellow sorbet over the red sorbet in an even layer. Place in the freezer for at least 45-60 minutes.
Repeat the above steps for the next 2 flavors of sorbet, ending with the white sorbet. Wrap the plastic wrap over the white sorbet and freeze for at least 12 hours to set.
Carefully pull the plastic wrap and the whole cake out of the cake pan. Place the cake on a clean work surface and flip it out of the pan holding onto the plastic wrap. (You don’t need to be too gentle, its frozen!) Place it cake-side down on a cake plate then ice the cake with whipped topping and garnish with lots of rainbow sprinkles.
Place the ice cream cones equidistant with the point cut-side down in a circle on top of the cake, so when you slice it, each piece has a “unicorn horn”. Store in freezer until ready to serve.MORE
: Buddy Valastro's Affogato How to Make Fake Cake Great CakeLemon-Buttermilk Pound Cake