How to Make a Sandcastle Cake

As I mentioned in Vivienne’s 2nd birthday post, we decided on a beach theme for her birthday party this year. I figure it’s the last year we’ll really be able to pick for her, and it seemed like it would be cute. Once that was decided and the invitations were ordered, I started browsing cakes. My initial searches focuses on “beach cakes” and I found a ton of ideas that incorporated edible sand. I figured I would be doing something with sand, but I wasn’t particularly inspired by any particular designs. Eventually, I stumbled upon a sandcastle cake and I was sold.

Sandcastles! It was perfect. And I want to share with you how I did it.

Now, if you search Google Images for sandcastle cakes, you get a lot of different variations. I pinned a bunch of them on Pinterest and figured I’d come back to it. And I did… but not until a couple of days before the party, when I was ready to bake cakes! I came up with a loose plan based on some of my inspiration cakes and decided to kind of wing it. I had a bunch of supplies on hand to incorporate—or not. It all depended on how it was going as I went along.

I had every intention of taking photos along the way. I started doing so on “assembly day” (the afternoon before the party), but things quickly got messy—just literally messy, my hands were constantly covered in frosting and “sand”—so the photos unfortunately fell to the wayside. But I’m going to try to do my best to describe and/or illustrate what I did. My kitchen was a disaster. There was a ton of cleanup involved. But overall, this was a pretty easy cake that I think even an inexperienced cake decorator can tackle. (Not saying I’m a professional or anything, but I’ve had a lot of practice over the years.)

So here we go. Let’s start with what you’ll need:

• (2) 9″ cakes and (2) 6″ cakes. (I used three batches of this doctored cake mix recipe. You’ll have extra batter.)
• Buttercream icing (I made a double batch of my favorite Wilton recipe.)
• 1 package of graham crackers
• 1 box of Vanilla Wafers
• Bag of marshmallows (“regular” size, like you’d use for s’mores)
• Chocolate candy melts (your choice of colors)
• Wilton seashell candy mold
• Toothpicks
• Cake circles
• Cake dowels

I like homemade baking, of course, but for making cakes like this—ones you need to stack, carve, shape, or whatever—I have not found a better solution than the “Durable Cake for 3D Cakes” recipe from Cake Central. Plus, it tastes so much better than regular ol’ box mix. Soooo much better. And as for buttercream, I always stick with the Wilton recipe because that’s what I learned with, and I don’t like to mess with it.

Vivienne’s party was on a Saturday. I baked the cakes on Thursday night. After they cooled, I wrapped them in plastic wrap to store them overnight. On Friday afternoon, Nora and I made the frosting and set up to start assembly.

STEP #1: Make the Edible Sand

Before we started frosting the cakes, I wanted to make sure we had the edible sand ready because I wanted to make sure to stick it to the cake before the frosting crusted over and became less sticky. So we started there. It was really simple: Take out your food processor. Throw in a bunch of graham crackers and vanilla wafers and process. Done.

I liked using the two ingredients in combination—the graham crackers and the vanilla wafers—for the slight variations in color, which is true of real sand. I thought it looked pretty realistic! Adding a couple of chocolate wafer cookies of some kind (not too many!) would probably make it look even better, but I liked my clean, “white” sand, too. :)

STEP #2: Level + Stack the Cake Layers

Now it was time to build this cake. You’ll want to stack your layers—just the matching ones at first. A quick note here: I always level my cakes before stacking. You know the “dome” that bakes on top of your cakes? That’s problematic when stacking. Even if it’s a subtle dome, it can make a big difference in the look and stability of your cakes. You can use a simple serrated bread knife to hack off the dome to give it a flat surface, or if you’re more OCD about it (like me), you can use one of these cake leveler doohickeys. I love mine, I seriously use it with nearly every cake I make.

So once they’re leveled, stack your 6″ cakes together (with a healthy layer of buttercream in between), then the same for your 9″ cakes. That’s where I’m at here:

You’ll see that before I put the 9″ cake on the cake board, I put some wax paper strips down around the edges then stacked the cakes on top (don’t put the wax paper ALL the way under the cake or you’ll have a hard time getting it out from underneath! that’s why you use strips and not one big piece). This is to protect the cake board from the icing so that you’ll get a nice clean look without gobs or smears of frosting on it. Also, in this case, it was critical to have the wax paper there to catch the excess sand as I was decorating.

The 6″ cake is also on a cake circle, by the way. I had some 8″ or 9″ plain cake circles in my stash and I cut one down to a small enough size so that it was just slightly smaller than the 6″ cake itself. That way, it would be easily hidden with frosting once I stacked my cakes.

So that’s where I stopped taking photos. I know, I suck.

STEP #3: Make Cubes to Use as Grooves on Top of Castle

Before you go any further, you should prepare your little squares to make your castle “grooves” on top of the cake. I did not do this at first since I didn’t have a plan—I iced everything and had to work VERY quickly (stressfully!) to make my squares so that my icing wouldn’t crust. I debated over how to make those little grooves at the top and came up with the idea to use marshmallows. But I wanted them more square than round, and wanted them smaller, so I used kitchen scissors to cut marshmallows into rough little cubes. That’s probably pretty self explanatory, but here’s a little diagram.

The dotted lines are my approximate cut lines. Just hack your marshmallows until you get cubes that are roughly the same size. :) Then, spear each of your cubes with toothpicks. Set them aside.

STEP #4: Ice and Stack the Cake Tiers, Add Cubes/Grooves to Top

Next, ice both cakes with your vanilla buttercream. You want to ice both cakes separately (your 6″ two layer cake and your 9″ two layer cake), before stacking your tiers. The nice thing about these cakes is that they’re going to be covered in sand, so you don’t have to be very meticulous with your icing. Just get a good layer on the cakes’ tops and sides and smooth it out a bit.

Now, let’s talk stacking of the tiers. When you have a multi-tier cake like this, you may be tempted to just throw the smaller cake on top of the larger cake. I’ve done this before, actually, in an effort to save time. It’s not worth it, because then I spend the next day—up until I’m cutting into it at the party—worried that the cake is leaning, it’s going to collapse, etc. So don’t just stack ’em. The cake is really a lot sturdier when you take the time to properly support it. I promise. For this cake, I used four wooden cake dowels to support the second layer. A good, simple tutorial for stacking layers is included within this blog post about making wedding cakes (scroll down and start at “Stacking Step #1”).

Once my cakes were stacked, I touched up the icing and made sure to cover the small gap between the tiers. Now, take the marshmallow cubes on toothpicks and use a butter knife to smear all sides with frosting. You don’t want to glob on the icing too thick because you want them to keep their shape, but get enough frosting on there that it’ll hold the sand. Once covered in icing, stick them onto the cake by pushing the toothpick into the top. This keeps them nice and securely attached to the cake.

STEP #5: Make the Doorway

Oh, and then there was the little “doorway” on the front of the bottom tier. I had to think on the fly for this one. At first, I thought maybe I could build up the icing enough to make the doorway shape out of the icing, but that was not going to work. Funnily enough, Nora was the one who initially suggested using marshmallows. At first, I didn’t think it would work, but then I happened to glance down at my marshmallow scraps. The ones from making my cubes for the top of the cake. They were small and thin and looked like they might actually do the trick. I picked up a few pieces and started rolling them between my hands (like you might do with Play-doh) and made little “snake” shapes with them. Sure enough, they stayed in that shape—didn’t rebound—so I was able to piece together little snake shapes and stick them onto the side of the cake to make the doorway. I again used a butter knife to cover the pieces in frosting.

STEP #6: Cover Everything in the Edible Sand

Now it’s time to get busy with your sand. It’s messy. Very messy. But I simply took my bowl of sand, grabbed handfuls, and then pushed sand onto the sides of the cake with my palms. It takes a few passes to get a good covering, but it goes quickly. Then, for the tops of the tiers, you can obviously just sprinkle sand over it—that’s the really easy part. Use your fingers to apply sand to the sides of your little marshmallow cubes, too. Once you have everything adequately covered in the sand, you’re done!

Carefully pull your wax paper strips out from underneath your bottom layer, which will clear away the excess sand with them. Do any necessary touch-ups (of frosting or sand) along the bottom of the cake.

STEP #7: Add Decorations and Embellishments

As a final step, you can add embellishments if you want. I made chocolate candy seashells using a Wilton mold. Just follow the instructions on the mold or your candy melt package, it’s really easy. Microwave the candy melts, pour/spread the melted candy into the molds, then pop into the freezer for a couple of minutes. Remove and ta-da, you have candy seashells. I positioned them on the cake to decorate it a bit. At one point, I also considered making paper flags to stick into the top layer but ultimately decided against it because I thought the seashells were enough. I’ve seen other versions where people use ice cream cones to make castle peaks on top, so get creative. Do your thing!

Everyone at the party loved the cake, and it tasted delicious, too! And our little girl had a wonderful 2nd birthday party.