Not Martha

Leprechaun Trap Cake

leprechaun trap rainbow cake

This may look like a perfectly innocent cake meant to lure a leprechaun to the top but it has a few secrets.

leprechaun trap rainbow cake

Secret #1: Beneath the pile of gold coins are fragile bars, when the leprechaun approaches to grab the coins he’ll fall into the pit and be trapped.

leprechaun trap rainbow cake

Secret #2: There is a rainbow hiding inside the cake. The leprechaun will discover this as he eats his way to freedom.

leprechaun trap rainbow cake

Have you heard of Leprechaun traps? I hadn’t encountered these until this year, and I am completely charmed by them. Leprechaun traps are created by kids in order to lure and trap a leprechaun. They are often a craft or sort of science experiment, there are some amazing ones collected here at Geek Dad. You can see plans for some at Family Fun (including the one that inspired my cake), and a round up at How Does She.

I decided that my angel food cake pan, with the hole in the middles, would make an excellent shape for a leprechaun trap. As bored kids growing up in suburbs we used to make traps similar to this for each other by digging a hole in the ground then covering it with a few fragile branches, a layer of leaves and finally topped with some loose grass to hide it. I’m shocked nobody ever broke an ankle.

To read the complete how-to for this cake please click on MORE.

leprechaun trap rainbow cake

To form the rainbow in this cake I used the method shown here at Omnomicon which is very simple — separate your cake batter, color each section, then pour it into your cake pan one color on top of the next. The first time I saw this method was when my friend Maggi (hi Maggi!) made one a few years back. (update: Maggi’s cake is over here. Pretty.)

The trouble: Usually when one makes a cake like this you divide the batter into equal parts but that results in the color that went in first spreading out more as it cups around the colors that come on top. The result is that when you cut a slice of the final cake you get less of some colors and more of others.

leprechaun trap rainbow cake

You can see this effect in the image above from Omnomicon, the color poured in last is much more prominent than the color that went first, which is squeezed and spread around the bottom.

I really hoped to create a more traditional rainbow arch and distribute the colors so they would result in more even appearance so I decided to change the ratio of the colors of batter. The color poured first (in this case red) was given more batter than the color poured second (orange) and so on, the last color (purple) got the least amount of batter. I think it turned out fairly well. (But I see some room for improvement in the future.)

leprechaun trap rainbow cake

So this is what I did. I used one box of white cake mix and separated the batter into eight bowls:

  • 6 ounces – red
  • 5 ounces – orange
  • 4 ounces – yellow
  • 3 ounces – green
  • 2 ounces – blue
  • 1 ounce – purple
  • 1 ounce – to be kept white
  • the rest of the batter, also kept white

I used an angel food cake pan, but if you have a more rounded bundt pan I think it would work out even better as it would look more like a hill. update: I’m doing some tests in different pan shapes and finding that rounded pans and taller pans (or more cake batter put in an angle food cake pan) doesn’t create the same arch shape. I’m doing all sorts of test (yay for reasons to buy more cake pans) and I’ll report back when I find out more.

leprechaun trap rainbow cake

To make pouring the batter easier I filled plastic bags with each color then snipped the corner just before I needed it. I think this gave me a bit more control than scraping it from a bowl, but be aware that it’s difficult to stop the batter once it’s started so get a good hold on the bag before you start — one hand should be on top to squeeze the batter.

leprechaun trap rainbow cake

This makes for pretty dishes.

leprechaun trap rainbow cake

First pour the larger amount of white batter into the pan. Then pour the red batter in, making it a wide ring of batter. Then pour the orange over that, keeping it inside the red. I found it was easier to control the ribbon of batter holding the bag a bit higher over the pan and trying to be zen about it.

leprechaun trap rainbow cake

Pour in each color, creating narrower and narrower rings. As you go along snip smaller corners off the bags, it will help you control the narrower shape you are trying to make.

leprechaun trap rainbow cake

Last pour the remaining ounce of white batter on top. I had hoped this would make the rainbow dome have a more hollow center but mine didn’t quite turn out, so you might not even bother with this last one unless you’re feeling ambitious.

Put the cake in the oven, you might consider baking it at 325 instead of the usual 350 as it will dome a bit less when baked at a lower temperature. I forgot to do this.

leprechaun trap rainbow cake

While the cake is baking you can create your pretzel ladder. I used milk chocolate candy melts as glue, dabbing it in place using a toothpick then setting the smaller pretzels on top. I held the pretzel rods in place by supporting them with quarters. You might want to remember to wash your quarters first if you anticipate anybody eating the ladder. Ooops.

leprechaun trap rainbow cake

Here is the ladder in better light. (I bake at night, it doesn’t make for great photos. My deep apologizes for the assault on your eyeballs.)

leprechaun trap rainbow cake

Level off what will be the bottom of your cake, this will also help shape the base of the rainbow arch as the batter will curve under itself creating more of a rainbow horseshoe.

leprechaun trap rainbow cake

Flip it right side up onto your cake plate, then slide a few rectangles of parchment paper under the edges so you can be messy while frosting the cake. When you are ready to present it you simply pull the parchment paper away and, ta da, an effortlessly clean cake plate. I learned this on the old Martha Stewart show. I miss that show.

To frost the cake I made a half batch of the Magnolia Bakery buttercream frosting recipe found at First I did a crumb layer, followed by a few minutes in the freezer. (It’s amazing I can make room in my freezer for something like this.)

leprechaun trap rainbow cake

I used at Ateco 234 tip, it’s one of the larger ones. Probably not the best for creating something like grass but I already owned it so I went with it.

leprechaun trap rainbow cake

I sunk some pretzel sticks over the middle hole in the cake to create a sneaky platform for our gold.

leprechaun trap rainbow cake

Then I simply piled foil wrapped gold coins over the pretzel bars.

leprechaun trap rainbow cake

I created a sign using the international image for “Hey, the end of the rainbow and the pot of gold are over here!”.

leprechaun trap rainbow cake

And stuck the sign into the cake using a popsicle stick.

leprechaun trap rainbow cake

leprechaun trap rainbow cake

Discoveries made:

  • You will stain your lips green while eating this.
  • My cake plate tilts to one side.
  • And I completely forgot to add the vanilla to the frosting.


  • Bake at a slightly lower temperature, say 325, to avoid doming.
  • If you use cake batter from scratch here is how I decided how much batter to separate out for colors — I took 2/3rds of the batter for color and divided that in amounts of 6/5/4/3/2/1 parts. In my cake the total batter was 34 ounces. Two-thirds of that is 22 ounces. Happily 6 + 5 + 4 + 3 + 2 + 1 = 21 ounces, which was close enough. YMMV (your math may vary).

Notes on different cake pan shapes:

  • I baked rainbow cakes in a bunch of different shapes of cake pans and took photos of the results. Turns out? The rainbow arch effect works best in the angel food cake pan. Otherwise the colors swirl a bit more, still very pretty but more tie dye than rainbow.

· comments [277] · 03-16-2011 · categories:food · holidays ·

277 responses so far ↓

  • 1 St. Patrick's Day Leprechaun Trap Cake - Clever Housewife // Feb 17, 2014 at 8:37 pm

    […] to Pinterest, last year, I found a Leprechaun Cake Trap, inspired by Not Martha. My twins each had one to take to class, and I was right – nobody else had a trap quite like […]

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    […] For Instructions click here..  […]

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    […] all heard of leprechaun traps, right? Well how about a leprechaun trap cake with rainbow filling? This cake by Not Martha has to be the most delicious leprechaun trap […]

  • 4 Seacoast Kids Calendar » Blog Archive » Go for the gold. Leprechaun Trap craft ideas. Gotcha! // Feb 26, 2014 at 2:12 pm

    […] This one’s actually a rainbow cake inside! Check out this link to see how to create the colorful layers. […]

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    […] This one’s actually a rainbow cake inside! Check out this link to see how to create the colorful layers. […]

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    […] how to layer the batter. My inspiration for creating my rainbow arch was from not martha and her Leprechaun Trap Cake that she created a few years ago. Her arch is so much more beautiful than mine. I highly encourage […]

  • 8 Kim Byers @ The Celebration Shoppe // Mar 9, 2014 at 6:43 pm

    Looks amazing! I shared in my recent roundup with Parade:

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    […] than just a tasty cake for those celebrating St. Patrick’s Day, this Leprechaun Trap Cakeactually features a pretzel trap (under the gold coins) that takes the mischievous leprechaun down a […]

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    […] up, the incredible Leprechaun Trap Cake from Megan, who blogs a lot of very cool stuff (not just Oirish cakes) at Not […]

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    […] Kitchen Jello Cookies by I Heart Nap time Mini Rainbow Vanilla Beam Donuts by Just Baked Leprechaun Trap Cake by Not Martha Rainbow Waffles by I’m Baker Rainbow Pudding by Makezine Double Vanilla […]

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  • 15 Leprechaun trap | Perennial Student // Mar 17, 2014 at 6:55 pm

    […] enjoy looking at some of the ideas other people have come up with, though. Another cute cake idea – similar in concept but quite different in appearance – has a rainbow hidden […]

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  • 17 Nicole Sims // Mar 4, 2015 at 6:32 pm

    I was wondering if you ever did a batter test with a bunt cake pan and if you think that would change the rainbow drastically?

  • 18 megan // Mar 4, 2015 at 6:43 pm

    Nicole – I didn’t do a bundt pan but I did test it out in an angel food cake pan, see here. I still don’t own a bundt pan, but should I come up with an excuse to get one I’ll try the rainbow cake.

  • 19 Claudia Sipac // Mar 11, 2015 at 2:07 pm

    I ll make this for my family this St. Patrick s day. It looks amazing.!!

  • 20 April // Mar 14, 2015 at 2:14 am

    Im making this for st pats too! Could you PLEASE tell me if you used 2 cake mix boxes?? I only bought one & thinking i have to rush out & get one more. Thanks,

  • 21 megan // Mar 14, 2015 at 7:45 am

    April – Yes, I used one box of cake mix. I made this in an angel food cake pan and after rising it was still only about half the height of the pan. Have fun!

  • 22 Mary // Mar 16, 2015 at 6:53 am

    Do you flip the cake before frosting? I’ve made this before and my rainbow was upside down. I can’t remember which way it should go…

  • 23 megan // Mar 16, 2015 at 10:28 am

    mary – The cake as shown is upside down to how it was in the pan. Or: as it bakes the top of the rainbow arch will be pointing to the bottom of the pan.

    I flipped it out of the pan, turned it over to trim the doming (on what will become the bottom of the cake), and then flipped it over again.

    Does that help? I hope it does!

  • 24 Marianne Allan // Oct 9, 2015 at 2:20 am

    In lieu of pretzel sticks why not use chocolate sticks – you can get ones with peppermint inside.

  • 25 Buffet Caterers Manchester // Feb 7, 2016 at 10:46 am

    Absolutely fabulous rainbow cake and secret #2 does it for me…. ‘There is a rainbow hiding inside the cake. The leprechaun will discover this as he eats his way to freedom’

  • 26 Kris // Mar 18, 2016 at 7:14 am

    I made this cake with my daughters and they absolutely loved it!! We made a chocolate funfetti cake instead of the rainbow. Sad that the leprechaun ate his way out of our cake and got away but they truly had a blast! Thank you so much for your wonderful idea!

  • 27 English Sweets // Apr 6, 2016 at 9:00 am

    This is one of the cutest things I have ever seen!!! Thank you for sharing :)

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