Adventures of a Cake Diva

A Blog About Adventures in Baking and Cake Decorating

Here Fishy, Fishy: How to Make a Cake Topper Using Rice Krispie Treats 04/29/2012

   I’ve had thirty-some birthdays in my life with just as many cakes to celebrate.  Most of them, I don’t remember.  Maybe you’re the same way.  But, there have been two cakes that I will never forget.  My mother made both of them for me when I was a child.

   When I turned five (or maybe six), my birthday cake looked like a giant hamburger.  Why did she make this cake?  Because, at that age, I would have eaten a hamburger for dinner every night, if she would have let me.

   For my eighth birthday, my mother converted our kitchen table into a Ms. Pac-Man board. She made several cakes–one for Ms. Pac-Man and each of the ghosts.  Why did she make this for me?  Because the pizza place that we frequented had a small arcade.  I always begged her for quarters so I could play Ms. Pac-Man.  When our pizza was ready, it was a bit of a fight to get me to the table to eat.  If it were up to me, I would have skipped dinner and kept playing.

   Both of these cakes said something about me, at that time in my life.  Because of this, I can still remember them (many, many) years later.  Maybe this is why I have a little bit of a soft spot for making birthday cakes for kids.

   This week, I made this birthday cake for a little boy.  While I was working away, I snapped a few photos of how I made the fish topper.  As I write this, I am feeling a bit like a magician who performs a trick and then shows the audience how it was done.  (For me, this is always a bit of a let down.)  I am really hoping that isn’t the case here.  Even though the construction is fairly simple (albeit time-consuming), I think the end result is still pretty neat.

Gradually build the shape.   Before you start, pull out a cake pan the size of the cake that your topper will sit upon.  This will help you to scale the topper to the correct size.  Turn the pan upside down, and place a cake board on top.    You can use a cake board that is the same size of the pan or a slightly smaller size.

   Place a small amount of room temperature Rice Krispie Treats (from now on, “RKT”) on top of the cake board.  Then,  sculpt the shape of the fish by gradually building it, layer by layer.  At this point, just focus on getting the general shape.  Since this cake was for a child, I wanted the fish to look cartoon-like and not too terribly realistic.  To achieve this, I made the fish’s body, and particularly the face, really round.  It doesn’t have to be perfect.  In fact, it won’t be perfect.  That’s okay.  This is a process, at least it is for me.

I know, I know. I need a manicure! 🙂

Fill in any gaps.  After you’ve shaped the fish’s body, take a good look for any gaps of missing RKT.  In the end, this “sculpture” will be covered with fondant, which will magnify every crevice.  Take the time to make sure that you have a solid base.


Fine tune the shape of the fish’s body.  Using your hands, mold (push) the RKT into the shape that you want for the body.  You’ll notice that some of the RKT will start to crush together.  This is actually a good thing.  You’ll have fewer craggy edges to contend with when you cover the sculpture with fondant.

   You might find that you need to remove some excess RKT.  Use a sharp knife to saw away the excess, a little at a time.  If you accidentally take off too much, no worries.  Just add more RKT to build the shape again.

   As you go along, take a couple of steps back from your work space, and look at the fish’s body from all angles.  Also, it’s helpful to take a few short breaks to reapproach the sculpture with fresh eyes.  The RKT will remain malleable for a good couple of hours, so you can take your time to some extent.

Once you have finished the fish’s body, or while you’re taking a break from sculpting, start working on the tail.  Using a ruler, figure out the width and length that you’ll need to make the tail.  Remember that you will have 1/8″-1/4″ of fondant that will cover the RKT.  You should subtract this amount from your length measurement, since it will reduce your surface space.  Add this amount to your height measurement, since the fondant covering will make your fish a wee bit taller.

Make a template for the tail and side fins.  Once you’ve figured out the tail’s measurements, draw a template for the tail.  The picture to the left shows my free-hand tail drawings.  Since I was aiming for a cartoonish look to the fish, I kept the shape simple and clean.  Cut out your tail drawings and hold them up to your RKT sculpture.  Make sure that you are happy with the tail size and shape.  You can also make a paper template for the two side fins, too.  I just cut them out of gumpaste free-hand with my X-Acto knife.

Using your paper templates, cut out two tails and side fins using gumpaste (preferred) or fondant.  Make 3-4 gumpaste cubes for the top fins.  Tint either gumpaste (preferred) or fondant an orange-yellow color.  This should be the same color that you will tint the fondant to cover the fish’s body.

   Using an X-Acto knife and your paper template as a guide, cut out two tails.  Lay the tails on top of each other, and insert in the middle 3-4 toothpicks.  In the picture to the left, I had just laid one tail on top of the other.  See the seam?  Take a dab of water to your finger and then rub the seam.  It will disappear.  I used my gumpaste tools to make a few markings on each side of the tail.

   Cut out the two side fins.  Also, shape 3-4 cubes of gumpaste (approximately 1/2″ tall) for the top fins.  Insert a toothpick into each cube.  All of these pieces will need at least 2 days to dry.  I always set my figures on a plate that has been sprinkled with cornstarch (prevents sticking) to dry out.

Cover the RKT sculpture with a thin layer of buttercream.   I always put a thick layer of buttercream on the RKT and then swipe away small amounts until a thin layer remains. Some cakers cover their RKT with white chocolate, rather than buttercream.  I’ve always used buttercream, and I’ve never had a problem.

I snapped this photo before smoothing the fondant.

Cover the RKT sculpture with fondant.  Use your fondant smoother to smooth out the fondant, just like you would for a cake.

Decorate the fish.  Make the eyes, mouth, and eyebrows from fondant.  Use a dab of water to apply these pieces to the body.  Cut out 3-4 ribbons of yellow fondant to make the side stripes.  Attach the fondant ribbons to the sides of the body with a tad of water.

   Insert 3-4  toothpicks into the top of the fish to create holes for inserting the toothpicks that are imbedded into each of the top fins.  Do the same at the rear of the fish to make the holes for inserting the tail.  Don’t try to insert the top fins or the tail without making these holes.  At this point, the fish’s body (RKT) is very hard, and you will run the risk of breaking these pieces.  Then, insert the top fins and the tail.

 Ta-da!  You’ve just made a cutie little cake topper!  Once you get the hang of it, you can make all sorts of cool things using these skills, like a fire truck, the neck of a bottle for a bottle cake, or a coral reef for a mermaid to rest upon.  Now that you know how it’s done, I hope that the magic hasn’t been lost for you.  I was still amazed when I made this fish and set it on top of the little boy’s birthday cake.


4 Responses to “Here Fishy, Fishy: How to Make a Cake Topper Using Rice Krispie Treats”

  1. mydearbakes Says:

    Loved this post, very insightful! =)

  2. Geraldine Says:

    Thank you for posting this! I definitely want to try it!! 🙂


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