Easy Guinness Chocolate Shamrock Cake Tutorial

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Happy St. Patrick’s Day, everyone! I hope you’re all doing as well as you can during this time. Please try to stay in as much as possible & lookout for the people around you. Baking is a great indoor activity to celebrate St. Pat’s. I’m half Irish, so this has always been my favorite holiday. Add in my love of holiday theme baking & I’ve been making something special for St. Paddy’s Day for quite some time now. My favorite dessert to make for this holiday is a Guinness cake. It’s absolutely delicious & so on theme that I can’t handle it. I switch up the presentation a little every year in a quest to constantly perfect the most perfect St. Patrick’s Day dessert ever. One year I made shamrock cupcakes, the next year a layer cake decorated with tiny buttercream shamrocks & last year I made shamrock whoopie pies. I decided to go bigger this year & make one big shamrock-shaped cake. I had to combine a few recipes to get this right, but without further ado, here is my recipe for green velvet shamrock cake.

Guinness chocolate shamrock cake picture
Hello, giant shamrock cake!


  • Guinness chocolate cake (I doubled this recipe & baked 2 cakes in a shallow rectangle pan).
  • Buttercream frosting (I used this recipe).
  • Green food coloring (I used leaf green from AmeriColors).


  1. Create a shamrock stencil. Place it over a baked & completely cooled cake & carefully carve out a shamrock with a knife. Repeat with the second layer of cake.
  2. Color the frosting with green food coloring. Frost the bottom cake layer, then top with the second cake layer & give the cake a crumb layer of frosting. Refrigerate for 15 minutes.
  3. Remove the cake from the fridge & add another layer of frosting, trying to make it as smooth as possible.
  4. Enjoy!
shamrock stencil picture
Shamrocks that my grandma made about 75 years ago.
Guinness chocolate cake picture
Guinness chocolate cake all ready to go.
Shamrock cake picture
It’s about to go down, after I washed the stencil, of course.


  • Take your time when carving the cake since it will crumble if you try to cut it too fast.
  • Save your cake trimming in a bowl. Snack on them or save them to be used in other projects like cake pops.
  • Be careful when frosting the cake, I had some issues with crumby frosting. Slow & steady definitely wins the race here.
shamrock cake stencil picture
Halfway there, it’s super easy.
shamrock cake image
Yay for stencils!
chocolate shamrock cake picture
First layer frosted & second layer placed.

I got this idea from a set of 3 laminated construction paper shamrocks that my grandma made maybe around 75 years ago. She was a teacher so they were her St. Pat’s classroom decorations. She gave them to me about 15 years ago & I have cherished them ever since. I always pull them out every St. Patrick’s Day & use them as centerpieces on my kitchen table. After I made shamrock whoopie pies last year, I decided to go bigger & use the biggest shamrock as my stencil this year. It’s neat to think that she made these over half a century ago & I used one of them to carve out a cake yesterday. These shamrocks have seen some things, I tell you what.

Guinness chocolate shamrock cake image
Guinness Chocolate Shamrock Cake complete.
From stencil to cake.

My father’s side is fully Irish, so she was my Irish American grandma, no surprise there. That side of my family is also where I got my love of gardening. It seems like the gardening bug hits all of us once we hit a certain age. We love celebrating this day like you wouldn’t believe. We all have our own traditions of making a traditional Irish feast & drinking Guinness, among other traditions. But making a Guinness cake might be my favorite tradition. What better way to celebrate the best holiday of the year than making (& eating) a giant, green shamrock cake? Go ahead, make your own, you know you want to! 

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