I made this sand castle cake for a little girl's 10th birthday pool party. I thought this was a great twist on the regular castle cake and it was really fun to do.
I baked 3 boxes of cake mixes into: two 8-inch square cakes, two 6-inch rounds, three large cupcakes, and 9 regular cupcakes. (I only used one of the large cupcakes and gave the extra two to my kids!) I cut the tops off the cupcakes and made stacks of three regular ones with a bamboo skewer through for each tower. I cut a niche out of the 2-layer square bottom cake to set the towers into. The 2-layer round was placed on a wax paper wrapped cardboard base and placed on the bottom cake after putting 4 plastic straws in for support. The top had one large cupcake (top sliced off) upside down. Upside-down sugar cones complete the towers and top. I used LOTS of frosting colored as close to sand color as I could get and covered it with crushed 'Nilla Wafers for sand. (I think it took close to a whole box.) It was tricky figuring out the order to assemble it to be able to frost and "sand" all the surfaces and how to get the sand up on the sides of the cake, but a basting brush turned out to work really well, gently brushing it up the sides and gently pressing it on the cake. Once the sand was on the frosting, I could use my hands to pat it smooth and even out the edges.
The finishing touches included shells and coral made from candy melts and shell molds. The flags made from candy melts with pretzel sticks and then written on with frosting. I cut the ends off the cones before frosting and placing on the cake so I could fit the pretzel sticks through the ends. I needed to "glue" the pretzels in by piping in candy melts and holding the flags in long enough for the candy to harden.
I also wrote the birthday girl's name in the sand to finish it off.