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Old Fashioned Buttermilk Chocolate Sheet Cake with Chocolate Frosting

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Old Fashioned Buttermilk Chocolate Sheet Cake…with a rich and silky chocolate buttercream frosting, of course! We are heading back to childhood with this chocolate sheet cake. Picture a rich, light, fluffy, and extra chocolate-y cake made in only ONE bowl, and extra thick. Then, add a silky, decadent, and roll your eyes back delicious chocolate frosting. It’s the ultimate chocolate cake that everyone is sure to love! Perfect for birthday parties, holiday’s, or simply just weekend baking. So. GOOD!

four square slices cut into chocolate sheet cake on parchment paper with flowers, sprinkles, plates, and a white cheesecloth around.

About The Recipe

Welcoming in June (and the first Friday of the month) with the best-ever chocolate cake!

There’s just something about summer that makes us crave nostalgic desserts, you know? And to us, there is nothing more nostalgic than a chocolate sheet cake!

And, yes, I know it’s technically not summer yet, the weather sure does feel like it here. It has been sunny and HOT! But, after all the cold and rain this winter and spring, I’m so thankful to see it.

Though, sharing a chocolate cake to “kick off summer” may seem a little odd.

Don’t worry. We have plenty of no-bake, frozen, and berry-filled treats planned for the coming days, but for the first of June, we just knew we wanted to share an easy-to-make chocolate cake.

Because, honestly, who doesn’t love chocolate cake?!

Plus, every summer, my mom always baked a chocolate cake. I think it was because it was something easy that – well, everyone loved!

So, if you’re in need of a delicious dessert that’s nostalgic, easy to make, and sure to be a crowd-pleaser…then you need to make this chocolate sheet cake!

slice of chocolate sheet cake on parchment paper with cake behind.

What is a Chocolate Sheet Cake?

A chocolate sheet cake can be made from a traditional butter based batter or, in this recipe’s case, from an oil based batter. The ingredients are relatively simple and the same as a regular oil-based cake – flour, sugar, cocoa powder, salt, baking powder, eggs, buttermilk, vegetable oil, and a splash of vanilla.

The secret to a delicious chocolate sheet cake is using buttermilk! This creates an intensely rich chocolate flavor, while making the cake tender and oh-so moist.

What’s The Difference Between Sheet Cake and Regular Cake?

Well, in terms of ingredients, both are the same! Just keep in mind that there are many different types of cake. Though, all of them can be made into a sheet cake!

The differences in the cakes actually come from how they are baked! A regular cake is typically made in a 6 inch or 8 inch round cake pan with multiple layers. A sheet cake is made in single 8×12 inch or a 9×13 inch sheet cake pan.

Reasons You Will Love This Chocolate Sheet Cake

  • Made in only 2 bowls (including making the frosting)! Which means…less dishes!
  • Super easy to make.
  • Perfect for birthday’s, weeknight/weekend desserts, or holiday’s.
  • Extra chocolate-y!!!
  • Effortlessly pretty.
overhead shot of cake with square slice cut into bottom left corner, with white flowers and sprinkles around, a white cheesecloth, white plates, and empty glasses around.

Equipment Needed

Ingredients

Full ingredient amounts and instructions can be found in the recipe card at the bottom of the post.

For The Cake:

  • All-Purpose Flour – We opted to use all-purpose flour rather than cake flour for this recipe to keep things as simple as possible. Though, don’t worry! The cake has almost no structural difference and is truly melt-in-your-mouth tender.
  • Dutch Process Cocoa Powder – This is important! Be sure that you have dutch process cocoa powder and not natural process cocoa powder or sweetened cocoa (hot cocoa powder). Dutch process cocoa gives this cake it’s intensely rich chocolate flavor!
  • Granulated Sugar – Sugar does so much for baked goods other than sweeten! It keeps the cake soft, moist, it helps promote browning…it is an essential ingredient for structure and flavor!
  • Salt – Cuts some of the sweetness, while also enhancing the flavors in this cake.
  • Baking Powder – Leavening is essential in baking! This provides the perfect rise in the cake to give is a light, tender, and delicious texture.
  • Large Eggs – Eggs add richness and moisture to this cake, as well as acting as a binder for the ingredients.
  • Buttermilk – Adding buttermilk to this cake not only intensifies the chocolate flavor, but it also helps keep the cake tender.
  • Vegetable Oil – Keeps this cake moist and oh-so tender.
  • Vanilla Extract – A splash of vanilla to enhance the chocolate, while also providing a full-bodied flavor in every bite.
salt, flour, cocoa powder, baking powder, sugar, milk, eggs, oil, and vanilla on marble surface.

For The Frosting:

  • Salted Butter – We always recommend that you use salted butter for frostings, as it helps enhance the flavor of the frosting and cuts some of the sweetness. Though, if all you have is unsalted, you can use that. Just add a pinch of salt!
  • Powdered Sugar – Be sure to sift the powdered sugar, as lumps in the powdered sugar can mean a lumpy frosting.
  • Dutch Process Cocoa Powder – Adds an intense chocolate flavor to this frosting, while also coloring it naturally.
  • Whole Milk – Using whole milk in this frosting helps loosen it to make it spreadable.
  • Vanilla Extract – A splash of vanilla to give this frosting a delicious undertone.
powdered sugar, vanilla, cocoa powder, butter, and milk on marble surface.

How To Make This Chocolate Sheet Cake

Step 1: Make cake batter

In a large bowl, whisk together flour, cocoa, sugar, salt, and baking powder.

Add eggs, buttermilk, oil, and vanilla. Whisk until smooth.

Step 2: Bake

Pour into prepared pan. Bake for 40 minutes, or until cake tests done.

Allow to cool in pan. Turn out, if desired.

chocolate sheet cake on wire cooling rack.

Step 3: Prepare frosting

Combine all ingredients in a large bowl. Beat with an electric mixer until smooth.

Step 4: Frost cake

Spread on cooled cake.

Frequently Asked Questions

How many will this cake serve?

This recipe is made in an 8×12 inch sheet pan and yielded 20 slices. If you desire to make this cake in a 9×13 inch pan, it will yield anywhere from 24-30 slices.

Why is my cake tough?

If your cake is tough, this is likely due to it being over-mixed. If desired, to prevent over-mixing, you can whisk the wet ingredients separately and gently stir them into the dry ingredients.

Why is my cake dry?

If your cake turned out to be dry, this is caused by over-baking. Always bake the least amount of time stated in a recipe, then check to see if it needs longer. You can also check your oven temperature to make sure it’s not running too hot.

Why did my cake not rise?

If your cake didn’t rise, this could be two things. Either the cake was over-mixed or your leavening is out of date. Be sure to check expiration dates before baking!

How to fix a cracked sheet cake?

The wonderful thing about this cake is, if it cracks, it’ll be covered by frosting and nobody will ever know! 😉

Why is my frosting lumpy?

A lumpy frosting could be caused by a couple of different things. If the butter or cream was too cold, then this would cause the butter to have small lumps in the frosting. If the powdered sugar or cocoa powder wasn’t sifted, this could also cause lumps. Though, no worries! If you keep beating the frosting, it should eventually smooth out.

Can I use a different frosting?

Absolutely! Cream cheese frosting or vanilla buttercream taste delicious with this cake.

cropped front shot of chocolate sheet cake with frosting on top with white sprinkles on a piece of parchment paper with three empty glasses and stack of white plates behind cake.

How To Achieve The Perfect Buttercream

There are are a few things you can do to make sure you get the creamiest, silkiest buttercream every single time!

The first is making sure your butter is room temperature. This is super important! Another is sifting your powdered sugar and cocoa powder. Lumps of powdered sugar and cocoa powder = lumpy buttercream!

Lastly, if you feel your buttercream is too thick, you can add a splash (1/2 – 1 Tablespoon) of whole milk or heavy cream. This will help loosen it a little.

Decorating Ideas

I think one of my favorite things about a sheet cake is how much fun they are to decorate! They’re so simple and always effortlessly gorgeous. Here are a few ways you can decorate this sheet cake!

  • Sprinkles, of any kind! Especially if you’re making this for a holiday party or birthday.
  • Chocolate curls
  • Edible flowers (such-as pansies, chamomile, or marigolds!)
  • Pipe a message with a vanilla buttercream. Feel free to color it!
  • Use piping tips to create a design with the frosting or simply pipe a border around the edge of the cake.
  • Top with chopped nuts.
four slices slightly pulled away from chocolate sheet cake on parchment paper with flowers and white sprinkles around on marble surface.

How To Store

Once this cake is made, it can be kept in a covered container and stored at room temperature for 2-3 days. It can also be stored in the fridge for up to 1 week!

This cake can also be frozen, if desired. Place sliced cake in a freezer safe zip-top bag or container and freeze for up to 2 months.

Substitutions

  • Don’t have buttermilk? No worries! You can make your own. Measure out 2 cups of whole milk and add 2 Tablespoons of lemon juice. Let it stand about 10 minutes.
  • This recipe can be made vegan by using a plant-based homemade buttermilk (follow the directions above but with oat milk or soy milk), your favorite vegan egg replacement (we love aquafaba!). For the frosting, use your favorite vegan butter and plant-based milk.

Looking for more recipes like this? Here are a few you may like:

The Ultimate Chocolate Cake

Chocolate Cupcakes with Chocolate Frosting

German Chocolate Cake

Flourless Chocolate Cake

Chocolate Mousse Cake

Homemade Ding Dongs

close up of cut chocolate sheet cake.

Expert Tips

  • Be careful to not over-mix the cake batter! If it’s mixed too much, the cake may become tough and not rise properly.
  • If you want a thinner cake, use a 9″x13″ pan. Remember to reduce cook time!
  • If you’re unsure the cake is baked after the time listed below, you can use a cake tester or tooth pick. If it comes clean, the cake is baked through!
  • Let the cake cool COMPLETELY before frosting it.
  • Make sure the butter and milk are room temperature before mixing the frosting.
  • Remember to sift the cocoa powder and powdered sugar!
  • If frosting is too thick, you can add a little more milk.

When you make this Old Fashioned Buttermilk Chocolate Sheet Cake with Chocolate Frosting, leave a comment down below! We love hearing from you and answering any questions you might have! Also, be sure to tag us on social media and hashtag it #BakersTable.

four square slices cut into chocolate sheet cake on parchment paper with flowers, sprinkles, plates, and a white cheesecloth around.
5 from 1 vote

Old Fashioned Buttermilk Chocolate Sheet Cake with Chocolate Frosting

Thick, extra chocolate-y, and SO DELICIOUS! This Old Fashioned Buttermilk Chocolate Sheet Cake with Chocolate Frosting is the perfect cake to bake for birthday parties, holiday's, weekend celebrations, or just as a weeknight dessert.
Prep Time: 25 minutes
Cook Time: 40 minutes
Total Time: 1 hour 5 minutes
Servings: 20

Ingredients
 

Cake

  • cups all purpose flour*
  • cup Dutch process cocoa powder, sifted
  • 1⅓ cups granulated sugar
  • 1 teaspoon salt
  • 1 Tablespoon baking powder
  • 3 large eggs
  • 2 cups buttermilk
  • ¾ cup vegetable oil
  • teaspoons vanilla extract

Frosting

  • Tablespoons salted butter, room temperature
  • cups powdered sugar, sifted
  • cup Dutch process cocoa powder, sifted
  • cup whole milk
  • 1⅙ teaspoons vanilla extract

Instructions
 

Cake

  • Heat oven to 350℉.
  • Spray an 8 inch x 12 inch pan with baking spray. Set aside.
  • In a large bowl, whisk together flour, cocoa, sugar, salt, and baking powder.
  • Add eggs, buttermilk, oil, and vanilla.
  • Whisk until smooth, about 1-2 minutes.
  • Pour into prepared pan.
  • Bake for 40 minutes, or until cake tests done.
  • Allow to cool in pan.
  • Turn out, if desired.

Frosting

  • Combine all ingredients in a large bowl.
  • Beat with an electric mixer until smooth.
  • Spread on cooled cake.

Notes + Tips!

*This recipe was written using an average of the dip and sweep method for measuring flour and the spoon and level method. If you are using a scale, you will need to add 3/4 oz or 22 g  to the measurement for each cup of flour.
Substitutions:
  • Don’t have buttermilk? No worries! You can make your own. Measure out 2 cups of whole milk and add 2 Tablespoons of lemon juice. Let it stand about 10 minutes.
  • This recipe can be made vegan by using a plant-based homemade buttermilk (follow the directions above but with oat milk or soy milk), your favorite vegan egg replacement (we love aquafaba!). For the frosting, use your favorite vegan butter and plant-based milk.
Expert Tips:
  • Be careful to not over-mix the cake batter! If it’s mixed too much, the cake may become tough and not rise properly.
  • If you want a thinner cake, use a 9″x13″ pan. Remember to reduce cook time!
  • If you’re unsure the cake is baked after the time listed below, you can use a cake tester or tooth pick. If it comes clean, the cake is baked through!
  • Let the cake cool COMPLETELY before frosting it.
  • Make sure the butter and milk are room temperature before mixing the frosting.
  • Remember to sift the cocoa powder and powdered sugar!
  • If frosting is too thick, you can add a little more milk.

Nutrition

Serving: 1slice | Calories: 310kcal | Carbohydrates: 44g | Protein: 5g | Fat: 15g | Saturated Fat: 5g | Polyunsaturated Fat: 5g | Monounsaturated Fat: 4g | Trans Fat: 0.2g | Cholesterol: 41mg | Sodium: 250mg | Potassium: 156mg | Fiber: 3g | Sugar: 28g | Vitamin A: 206IU | Calcium: 84mg | Iron: 2mg

Nutritional information is only an estimate. The accuracy of the nutritional information for any recipe on this site is not guaranteed.

When you make this recipe, remember to tag @bakerstble or hashtag it #BakersTable!

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