Gluten-Free Chocolate Sheet Cake

Get ready to make the most delicious, moist, and tender gluten-free chocolate sheet cake! Forget grocery store cakes that are filled with gluten and artificial dyes. My gluten-free chocolate sheet cake takes the cake when it comes to birthday parties, potlucks, and whenever the occasion calls for a celebratory cake. This post contains affiliate links. Please see my disclosures.

My mom always ordered a chocolate sheet cake from the grocery store to serve at my childhood birthday parties.

I remember the cake was rich and chocolatey and always included a delicious buttercream frosting. It didn’t hurt that it was decorated with colorful balloons and had the words “Happy Birthday, Jenny” written with frosting across the cake.

Unfortunately, after going on a gluten-free diet more than a decade ago after being diagnosed with celiac disease, grocery-store chocolate sheet cake became a thing of the past.

I decided it was time to make a gluten-free chocolate sheet cake that I could enjoy. This cake is reminiscent of a grocery store sheet cake, only mine is made with gluten, a protein found in wheat, rye, barley, and sometimes oats. This rich and chocolatey cake makes me feel nostalgic and evokes memories of simpler times.

Ingredients for Chocolate Sheet Cake

You’ll need a few simple ingredients to make this gluten-free chocolate sheet cake. I also note several substitutions along the way:

The first thing you need is to select a good flour blend. I used Better Batter All-Purpose Gluten-Free Flour, which worked beautifully in this recipe. If your flour blend doesn’t contain xanthan gum, add ¾ teaspoon of it. Better Batter already contains xanthan gum, so I didn’t add more.

Then you’ll gather up the brown sugar, cocoa (or cacao), baking soda, salt, brewed coffee, vegetable oil, eggs, and buttermilk.

To make buttermilk, combine 1/2 cup of whole milk with 1 tsp of lemon juice. Allow the mixture to sit at room temperature for 5-8 minutes to curdle lightly. You can also use sour cream or [dairy-free] yogurt instead of buttermilk.

How to Make the Cake

Preheat the oven to 325°F and lightly grease a 9×13 pan. Set it aside.

In a large mixing bowl, whisk the gluten-free flour blend and xanthan gum (if needed), brown sugar, cocoa, baking soda, and salt.

Add the hot brewed coffee and oil to the dry ingredients, then stir the ingredients using a spatula or spoon until you see a smooth dark batter.

Next, add the buttermilk (or sour cream or yogurt) and eggs and stir the ingredients with a spatula or spoon until well mixed.

Now fill the 9×13″ cake pan with the batter and spread it evenly in the pan. Bake the cake for 35-40 minutes or until it springs back when gently touched or a toothpick inserted near the center of the cake comes out mostly clean.

Let the cake cool completely, then add your favorite frosting. I’ve included a simple buttercream frosting recipe in the recipe card below.

If you’re a good cake decorator, you can decorate the cake so it looks like one of those grocery store sheet cakes complete with buttercream flowers and balloons and a happy birthday message written in script.

However, if you’re anything like me, frosting is about all the decoration you’re capable of, so swirls of buttercream will have to do!

Now divvy up this beautiful, moist, tender, and tasty chocolate cake and enjoy. You can slice and serve it directly from the sheet pan.

FAQ & Substitutions

Freezing Instructions: You can freeze the unfrosted cake for a month in your freezer. Then frost and thaw the cake before serving.

Storing Leftover Cake: Store leftover cake in an airtight container at room temperature for up to three days or in the fridge for up to a week.

Buttermilk Options (Dairy-Free): If you don’t have buttermilk, you can make it by adding 1 tsp of lemon juice to the whole milk. Let it sit at room temperature for 5-8 minutes. I find it challenging to make buttermilk with dairy-free milk (it doesn’t curdle in the same way), so I suggest instead using either dairy-free yogurt or full-fat coconut milk (from a can) plus 1 tsp of vinegar. Both options make good dairy-free substitutions. You could also use sour cream (not dairy-free) instead of buttermilk for an intensely moist cake.

No Coffee? If you don’t want to brew a cup of joe, you can omit the coffee and use hot water instead. However, I recommend brewed coffee because it deepens the chocolate flavor and gives the cake a better overall taste. I used decaf instead of coffee. (Read: Is Coffee Gluten Free?)

For the Frosting: You can use store-bought frosting or my simple buttercream frosting recipe:

• 3/4 cup butter or dairy-free butter (1 and 1/2 sticks) – room temperature
• 3 cups powdered sugar
• 2 tsp vanilla
• 2 tbsp milk or dairy-free milk

Beat the butter in a standing mixer until smooth. Add the powdered sugar, vanilla, and milk and beat until light and fluffy. If the frosting is too thin, add more powdered sugar. If it’s too thick, add a bit more milk. Spread the frosting on the cake, cupcakes, or layered cake.

Pan Options: This recipe is highly versatile. You can make cupcakes or a layered cake instead of a sheet cake.

• For cupcakes, prepare a 24-cavity cupcake pan with liners. Divide the batter evenly and bake for 20-25 minutes.
• For a layered cake, prepare two 9-inch pans with parchment paper (cut the parchment paper into a circle and line the bottom of each pan) and lightly grease the pan and paper. Bake the cakes for 30-35 minutes.

Here’s how my layered cake and cupcakes look:

This cake is extremely versatile, perfect for birthday parties, potlucks, and whenever the occasion calls for cake, which is often in my house. It will deliver time and time again with its tender and moist texture and deep chocolate flavor. Enjoy!

More Recipes

You might enjoy these recipes, too:

• Gluten-Free Chocolate Cupcakes with Raspberry Buttercream
• Favorite Gluten-Free Chocolate Applesauce Cake
• Amazing Gluten-Free Banana Cake with Cream Cheese Frosting