Optical Illusion Cake Tutorial

This tutorial demonstrates how to make an optical illusion cake using three different tones of rolled modeling chocolate. This is a 2-dimensional design that gives the impression of 3-dimensional cubes so it’s a neat trick and it’s fairly easy to do.

VIDEO: Optical Illusion Cake

Below is a photo transcript of the video with links and additional tips. Here are my recipes for modeling chocolate and videos on how to roll modeling chocolate. This round wedding cake was frosted with smooth vanilla buttercream.

Optical Illusion Cake

To start, you need white modeling chocolate, dark modeling chocolate and a combination of the two. The lighter chocolate color can be made by kneading half and half dark and white modeling chocolate together.

Optical Illusion Cake

Begin by rolling out the modeling chocolate into thin sheets.

Optical Illusion Cake

Using a 2″ diameter or 51 millimeter (measured tip to tip, which) hexagon cutter, begin by cutting the same shape out of all three colors of rolled modeling chocolate.

Optical Illusion Cake

Then cut each hexagon into three pieces to make three equal sized diamonds. If you happen to have a diamond cutter that works for this design, go ahead and use it. The problem is that most diamond cutters aren’t quite the right shape to make it work.

Optical Illusion Cake

However the hexagon cutter works well. The trick is to use the opposite point as a guide (see video above). Align the first two cuts in the direction of their opposite points. Then cut the remaining V-shape in half. That way, the diamonds should come out the same.

Optical Illusion Cake

Ready the pieces on a sheet pan so that they are all lined up with each hexagon containing all three colors.

Optical Illusion Cake

Some of the triangles of one color will need to be cut once more the long way down the middle to create bottom pieces.

Optical Illusion Cake

Once the cake is frosted with buttercream and chilled, begin assembling the design, working with the bottom pieces from the bottom of the cake up. The first row is medium chocolate bottom pieces. The second row is a dark and white chocolate zig zag. The third row is sideways medium chocolate diamonds. The fourth row is dark and white chocolate zig zag except the position of the colors is reversed. The fifth row is another layer of sideways medium chocolate diamonds. And so on and so forth.

Optical Illusion Cake

You can adjust the position of the modeling chocolate diamonds by sliding them around on the cold buttercream frosting.

As an alternative to placing the pieces directly onto the cake one by one, you can also pre-arrange the pieces on strips of acetate then press them onto the sides of cake and peel away the acetate gently, kind of like a press-on tattoo. Modeling chocolate loosely sticks to acetate without any adhesive so it makes the perfect transferring medium. Once the pieces are on the cake, if they need to be shifted or re-arranged at all, do it right away before they bond with the cold buttercream frosting.

Follow this link to see my video tutorial on how to make easy modeling chocolate fabric roses.

Modeling Chocolate Roses

 Here is the final product:
Optical Illusion Cake
Cake stand by Shannon of Batter Up Cake Co.

I invite you to share a photo of your work below in the comment section so that others can find inspiration in your own unique interpretations. If you run a cake business, be sure to tag it.

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Cake Decorating with Modeling Chocolate

Cake Decorating with Modeling Chocolate

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Smooth Buttercream Cake Frosting

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Comments

Optical Illusion Cake Tutorial — 64 Comments

  1. hi i was wondering how to i count the size of the hexacon so i dont get overlap or that it doesn’t close great cake love it also the modeling chocolate amazing to work with

    • Looks great! My preference over trying to get decorations like this to meet perfectly (which is nearly impossible if you are working with a multi-tier cake since each tier then has a different circumference) is to bring the pieces to the point of overlap then slice through them using a craft utility knife, making a straight vertical line. Peel away the excess so the design zips together flush. There will be a seam there where the pattern appears disrupted. Pipe a vertical row of buttercream dots right on top of that seam. Make a continuous row of small pearl-like dots as you would pipe around the base of a cake. It will look like a row of buttons, as per the back of a dress. In fact it will look as if it’s meant to be there. In my opinion, this is the best way to deal with design seams on cakes.

      If the cake is to be displayed against a wall, I wouldn’t bother with this level of detail. Then I would simply turn the seams to face the wall, where nobody can see them. Only in the case when a cake is to be displayed in the center of a room do I bother dressing up the seams, because then people can see them.

      • thanks for your quick response and tips
        thus cake I wanted to make already long time and it turned out great thank you again

  2. I am planning to make this cake soon and I’m wondering if I can do it with two tone chocolate, do I get the same results as yours for optical illusion? thanks.

  3. Wow! brilliant! I am from Tonga and we don’t have supplies here but I will definitely try and get the right tools and make this cake. Very inspiring and I know it will take a while for me to get the right tools but the time will definitely come. Will post it when that time comes. Thank you for this awesome technique.

  4. I couldn’t wait to try this cake! So excited! Thank you for the tutorial, it lead me every step of the way. I did change it by using all fondant instead of chocolate…

    • Hmm…not sure. I didn’t time it and I was filming the whole time so that slowed the whole process down a bit! On the first day, I rolled out the modeling chocolate and cut it into shapes. On the second day, I used them to decorate the cake. It was definitely more tedious than your average cake but well worth it!

    • If you happen to have a diamond cutter that works for this design, go ahead and use it. The problem is that most diamond cutters aren’t quite the right shape to fit together into a hexagon. If I were you, I would test our your diamond cutter to see if it works. If not, use a hexagon cutter then cut its shape into three equal-sized diamonds with a knife.

  5. Thank you so much for your tutorial! I made my father-in-law’s 70th birthday cake using your tutorial. I didn’t leave myself enough time, so its not brilliant, but it gave the illusion effect and everyone was impressed. Thank you 🙂

  6. I am so glad to have found your site and blog, I love working with chocolate and your instructions are simple and clear, cant wait to try

  7. That’s incredible…can’t wait to try it! What did you do to make sure the pattern “fit” properly around the circumference? (e.g. what happens if the spacing doesn’t work out, and the last pieces don’t meet up with the first ones)? Did you measure it all out using your cutter first? Or did you adjust the spacing once you had completed the base row?

    • That’s a good question. Thank you for asking as I’m sure other readers are wondering the same thing. No, I didn’t measure, I just winged it…but I did make sure to use a round cake since this design is more difficult to do on a square. On round cakes, ultimately, there is always a seam at the start/stop location where the pattern meets. I call this the “back” of the cake and I turn that part out of sight so that no one can see it (provided the cake is displayed against a wall). If the cake is to be displayed in the center of a room, I would complete the pattern as best as possible then pipe a row of buttercream dots down the seam to cover it up. That gives cakes the intentional look of a zipper or row of buttons, as if the pattern is made of fabric and that’s where it was closed up. Alternatively, you could cover up that seam with some more chocolate flowers or another decoration of some sort. The key is to make it look natural, as if you meant for that decoration or row of dots to be there all along.

  8. Very impressive. Is it ok to try the technique? Can you do it with different coloured fondants? Thanks heaps. Very inspirational.

  9. Thank you so much for sharing. I made a cake a couple of months back that had one side with this pattern, and oh boy, was that difficult! I can’t wait to use your technique! Thanks again!

  10. How do you determine the amount of modeling chocolate to make when you are creating projects like this? I know it’s better to have too much than not enough, but what’s the best way to determine that?

    You are so talented and very considerate for sharing your great ideas and tutorials!

    Thanks!

    • You are very welcome. How much modeling chocolate you need depends entirely on how thinly you roll it. If you lay it on thickly like fondant, a batch will be gone in no time. If you roll it quite thinly, it will last much longer. It takes practice to learn how to roll it that thinly though. So for that 3-tiered 6″ 8″ 10″ cake, I started with two batches of dark modeling chocolate and two batches of white modeling chocolate. I had a lot left over in the end, which was my intention all along. I prefer to have extra rather than risk not having enough.

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