Mexican Chocolate Sheet Cake [GF]

In September we had a backlog of celebrations to catch up with on account of the pandemic. It’s been a strange year, what with gatherings constrained and people being very careful not to contract the virus. We have been lucky so far, but also extremely careful, yet when the August and September birthdays rolled in, we felt like it was important to observe these celebrations more than ever. The pandemic has forced us to look at the pattern and shape of our lives. Old rituals have vanished and new ones have emerged. The rhythm of life has had to slow down from staccato to andante, and celebrations in particular have lost a little bit of their shine when we can’t gather together as we used to do before. Almost every facet of life has changed in some way or had to be adapted, and one of those means spending time on Zoom with friends and family for gatherings and celebrations instead of being under one roof.

However, even if we can’t gather in person with friends and family, either because they are in another state or because it’s not safe to do so, we can still observe birthdays, and so this recipe was born as a way to observe the birthdays of my two nephews who live in North Carolina. Little Henry’s birthday was a scant two weeks ago and, in his honor, I created this moist, rich, and decadently chocolatey gluten-free birthday cake. I had a significant amount of buttermilk left over in the fridge after making weekend pancakes, so I wanted to create an easy chocolate cake recipe that would quickly come together and could soak up all the rich goodness of the buttermilk and yield an extra moist cake. The fact that it is made in a rectangular baking pan allows it to share in an easy way without making a fuss. It also cuts down on the time you have to spend on unmolding and decorating the cakes, something that can be very practical when serving birthdays of young kids. A sheet cake really does make it a simple, straightforward, and still delicious way to produce a birthday cake.

The gluten-free chocolate cake was so good that almost all of it was gone by evening. There wasn’t even any left for breakfast! It is topped with a thick swirl of Mexican chocolate buttercream, and the buttermilk does a good job of keeping the cake crumb moist when using the gluten-free flour. The cake is light and fluffy. If you don’t have buttermilk on hand, you can always create your own substitute: for every cup of buttermilk, simply use 1 cup of milk plus 1 teaspoon of lemon juice mixed in, and let the milk and lemon juice stand for 5-10 minutes. I hope that wherever you are, you will continue to celebrate life’s milestones and observe all of the events that punctuate life and give us joy and meaning. I hope you will give this cake a try too! It’s going to taste amazing, I promise.

Mexican Chocolate Sheet Cake

Prep time: 20 mins

Cook Time: 35 min.

Assembly: 15min

Servings: 8-10

Chocolate Cinnamon Cake


  • 1 ¾ cup sugar
  • 1 cup cocoa powder
  • 1 ¾ cup gluten-free flour
  • 1 ½ tsp Celtic salt
  • 1 tsp cinnamon
  • 1 tsp ground vanilla powder
  • 1 ½ tsp baking powder
  • 1 ½ tsp baking soda
  • 2 eggs
  • ½ cup butter
  • 1 cup buttermilk
  • 1 tsp vanilla extract
  • ¾ cup water

Chocolate Cinnamon Buttercream


  • ¾ cup unsalted butter, softened
  • 2 ¼ cups powdered sugar
  • 1 tsp vanilla extract
  • ½ tsp cinnamon
  • ¼ cup cocoa
  • ¼ cup whole milk
  • 4 oz semi-sweet chocolate, melted and cooled
  • 3 tbsp sprinkles


Make the Cake

  1. Preheat the oven to 350°F.
  2. Butter and flour an 8x13x2 inch rectangular baking pan and set aside. Remember to dust the pan with gluten-free flour as well and avoid using regular flour.
  3. In a medium bowl, whisk together the eggs, buttermilk, and butter until smooth. 
  4. Add the vanilla extract. Set aside.
  5. In a separate bowl, combine the sugar, cocoa, gluten-free flour, cinnamon, baking powder, baking soda, ground vanilla, and salt. Mix well with a whisk and create a small well in the center.
  6. Meanwhile, heat the water and, when it reaches the boiling point, remove from the heat and set aside.
  7. Pour the egg/buttermilk batter into the dry mixture gradually, mixing constantly to avoid granules from forming. If it gets too thick, alternate with the boiling water, until it is completely incorporated. The cake batter will be thin and fairly liquid. 
  8. Pour the batter into the prepared rectangular baking pan and bake at 350°F for 35 to 40 minutes, or until a toothpick inserted into the center comes out clean. To check for doneness, no moist crumbs should cling to the toothpick. If it’s moist, then the cake needs to continue baking until it comes out clean.
  9. Remove the cake from the oven and fully cool in the pan for about 40 minutes. If you’re serving it as a sheet cake, as I did, you don’t need to remove it from the pan.

Make the Chocolate Frosting

  1. In the bowl of a stand mixer with whisk attachment, beat the butter until smooth and creamy.
  2. While the butter beats, combine all the dry ingredients in another bowl.
  3. Gradually add the dry ingredients to the beaten butter, followed by the vanilla extract. 
  4. Gradually add the milk until incorporated, then turn the beater to high, beating until it is very fluffy.
  5. Finally, add the melted chocolate, beating well until fully incorporated.

To Assemble

  • To assemble: spread the frosting on top of the sheet cake and, using an offset spatula, create a swirling motion to form a curved pattern. Sprinkle with colorful funfetti on top.

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