How to Make an Impressive Shark Diorama Cake

This ocean-scene creation is meant to be admired from all angles.

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Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

Photo By: Heather Baird

So Much to See

Before you slice into this cake, make sure your guests have a chance to take it all in! This colorful ocean scene (complete with circling sharks) is only half the design — the other side of the cake is covered in stealthy shark silhouettes, inviting the viewer to enjoy the creation as a 3D scene. Here's how to make it.

Choose Your Cake

For thisr project, bake your favorite cake with a sturdy crumb that'll stand up to a little carving. This cake consists of three tiers: You’ll need four 9-inch cake layers for the bottom tier, four 8-inch layers for the middle tier and four 6-inch layers for the top tier.

Take a Spin

If you're going to dive into this cake, we recommend you get cake turntable. It will make the work of building and decorating much easier.

Spread Frosting

Frost the first cake layer with an even layer of your favorite buttercream frosting. You can tint the frosting blue as shown or leave it untinted, if you want the cake to be all-white on the inside. You will need about 4 cups of buttercream to fill and crumb-coat the cakes.

Stack it Up

Stack and fill the remaining cake layers. Examine the cake on all sides to ensure the sides are as even as possible. Repeat the process with the remaining cake layers for the 8-inch tier and the 6-inch tier.

Add the Crumb Coat

Coat the exteriors of the cakes with a thin layer of buttercream (this is the crumb coat) and transfer the cakes to the refrigerator to chill until firm, about 30 minutes to 1 hour.

Make Ganache

Prepare a ganache by mixing chocolate chips and hot (not boiling) heavy cream in a 2:1 ratio. You’ll need about 4 cups of ganache for this recipe. The ganache will be thin at first, so let it stand at room temperature to thicken, about 1 hour. Stir intermittently until the mixture is of spreading consistency.

Frost Again

Frost the cake with a thin layer of ganache and smooth it using an offset spatula.

And Twice More

Frost the remaining tiers with the ganache and refrigerate until firm, about 1 hour.

Supply Reinforcements

When the cakes are well-chilled and firm to the touch, insert a few support dowels to the top of the cake, a bit off-center (since you're going to carve out a decent amount of one side of the layers.) Stack cakes and repeat with the middle and top tier, positioning the layers so that all of the support dowels are to one side of the cake.

Carve it Out

Use a toothpick to draw a zigzag outline into the ganache down all three cake tiers (it looks like a shark bite!). Take a knife and carve about a third of the cake away inside of the pattern, creating a hollowed out effect.

Prep More Buttercream

You’ll need about 8 cups of your favorite buttercream frosting, divided into approximately 1 1/2 cup portions. Tint each portion in a different intensity of blue so you can create an ombre effect. Reserve 1/2 cup of white (untinted) frosting reserved to frost the top of the cake.

Frost the Scene

Frost shark bite cut-out starting with a pale color of blue buttercream towards the bottom of the cake, and use a medium shade of blue to frost the top two tiers. It’s OK if the colors mix together slightly as you frost the cake — this will only add to the ocean-y, watercolor effect.

Create Shark Templates

Print out some shark clip art and cover with parchment paper. Use a food color pen to outline the shark silhouettes and then cut them out with scissors.

Stencil the Sharks

Starting on the bottom tier of the cake and using the darkest hue of blue buttercream, hold a shark stencil onto the ganache and use a small offset spatula to spread frosting around the stencil. Make sure to cover all of the stencil’s edges, and leave the center of the stencil unfrosted so it is visible for you to remove later. Repeat the stenciling process over the entire cake, and as you travel upward, use lighter shades of buttercream as you frost.

Reveal the Sharks

Use a toothpick to find the edges of the stencil and gently pull the stencils away from the surface of the cake revealing a shark silhouette.

Get Sandy

Transfer the cake to a large sturdy serving tray or platter. Spread leftover dark blue buttercream around the bottom edges of the cake. On the cut-out side of the cake, sprinkle 1 1/2 cups graham cracker crumbs over the frosting to achieve the appearance of a sandy ocean floor.

Make (Tasty!) Fondant

Marshmallow fondant is a wonderfully delicious way to make the embellishments for this cake. Combine 3 cups mini marshmallows and 1/2 tablespoon of water in a large bowl and heat in the microwave until the marshmallows puff and the mixture can be stirred smooth.

Pull it Together

Add powdered sugar to the melted marshmallow a cup at a time, and mix until well incorporated. After about 2 cups of sugar, the fondant will become thick and too difficult to stir. At this stage, lightly dust a work surface with powdered sugar and knead until smooth and pliable. It should be firm and hold its shape well when you roll it into a ball. If the fondant relaxes and loses its shape then knead in more powdered sugar until firm.

Tint the Fondant

Divide the fondant into six equal portions and tint each with gel food color to your liking. Wear gloves to knead in the color to avoid staining hands. Tint at least two portions of fondant grey using small amounts of black food color. These portions of fondant will be used for creating the sharks on the cut-out side of the cake, and the fins on top of the cake. Tint one portion red, one portion green one portion purple, and leave one portion untinted (white).

Make Red "Tube" Coral

Using a rolling pin, roll the red fondant to 1/4-inch thickness. Cut away a 1 1/2-inch piece and roll up jellyroll style until you have a small tubular shape. Trim the cut end away so that the piece is about 2-inches tall. Pock the outside of the tube with a toothpick. Repeat until you have many pieces of coral. Set aside to dry until firm, about 30 minutes.

Make White "Brain" Coral

Divide the white portion of fondant into gumball-sized pieces. Use the opening of a French pastry tube to pock the balls of fondant. Use a toothpick or fondant tool to press indentions into the fondant. Set aside to dry until firm, about 30 minutes.

Make Green Kelp

Roll the green fondant to 1/4-inch thickness on a work surface. Using a small paring knife, cut the fondant into 4, 6, and 8-inch lengths, each about 1/2-inch thick wide with a pointed end resembling kelp. Twist the pieces and set aside to dry until firm, about 30 minutes.

Make Purple "Mystery" Color

Get creative with your coral shapes! Roll purple fondant to 1/4-inch thickness on a work surface. Cut rectangles from the fondant approximately 2x4-inches. Use varying sizes of cake decorator piping tips to cut holes in the pieces. Set aside to dry until firm, about 30 minutes.

Make More Sharks

Print another shark silhouette template and lay it over a grey piece of fondant that has been rolled to 1/8-inch thickness. Use a craft knife to cut around a shark silhouette through the paper and through the fondant. Remove the paper and remove excess fondant from the cut-out. Repeat process to make a second fondant shark. Press a single black sugar pearl into the fondant for the shark’s eye, and draw on gills and other details using a food color pen.

Make Starfish

Create candy starfish and shells using candy melts and a specialty mold. To shortcut this step, find ready-made chocolate shells and starfish in the candy aisle at most grocery stores.

Create Your Scene

Press fondant coral pieces in the graham cracker ‘sand’. Be sure they anchor into the frosting so they will stand upright.

Add Kelp

Place kelp strands upright in the graham cracker sand, and use dots of leftover buttercream to attach the kelp to the cake.

Keep Going!

Place purple mystery coral upright in the sand. Decorate the sandy ocean floor further with candy pearls, candy starfish and shells.

Embellish the Sharks

Use small and large sugar pearls to create air bubbles that appear just above the sharks’ heads.

Add Fishies

Ready-made colorful candy fish can be tacked onto the cake with extra buttercream. Grouped together they make a convincing school of fish!

Finish With Fins

Roll remaining grey fondant to 1/8-inch thickness. Using a round 5-inch cookie cutter, stamp a shape from the fondant. Cut the circle into quarters and using the same cutter, stamp a small piece from a flat edge creating a shark fin shape. Allow the shapes to dry until firm. Frost the top of the cake with white buttercream and sprinkle on white nonpareils. Press the shark fins into the top edges of the cake, as if they are circling.

Show It Off!

Display the finished cake on a table where guests can examine all sides of the cake at eye level. The silouhettes offer a fun hint at what can be found on the other side!