Bake cake and allow it to cool completely.
While cake is baking and cooling, prepare the frosting.
Place the cake on a serving dish.
Use a serrated knife to trim the sides and dome.
Use a spatula to ice cake smoothly in chocolate frosting.
Stick Kit Kat bars around the cake. The frosting works like "edible glue."
Arrange 4 Kit Kats close together on a sheet of wax paper to make the top lid of the box. I had to add a single Kit Kat piece to my arrangement because the size was not matching up with the cake.
Use melted chocolate to stick all these Kit Kats together and let this lid set and harden.
In the meantime, fill the top of the cake with gold and silver candies.
Push a bamboo skewer into both sides of the cake. I used bamboo cocktail forks. The lid will rest on these skewers.
Brush melted chocolate generously near the back of the box and stick the chocolate lid here. The lid should be partially open and resting on the skewers. You will have to hold the lid for about a minute to help keep it secure until the chocolate sets.
Use a dry brush to randomly spread cocoa powder all over the box (top, sides, front, back). This will give it a rustic appearance.
Fill the box with some more gold and silver candies to make it look like it's overflowing with treasure.
Create the setting now. Spread brown sugar around the box to represent sand. Use scissors to cut a red Twizzler and place it in an "X" shape near the box. Spread gold and silver candies randomly around the board. Also, add some chocolate balls in the "edible sand" to represent stones and pebbles. Enjoy.