Chocolate Sheet Cake

My chocolate sheet cake recipe has been a favorite on the blog for years! It is irresistibly moist and soft, almost fudgy in texture. This recipe makes a large cake (it serves 15 to 20!) that’s ideal for a big gathering like a birthday party.

My team recently retested this delicious dessert recipe with foolproof results and a cake that stays moist for days. We found that vegetable oil and sour cream are a must for an incredibly soft, fudgy cake. And you’ll never guess the secret ingredient for a luscious frosting: hot fudge sauce!

A reader, Mary, says: “This cake is incredibly moist and delicious! I doubled the recipe and made a ganache filling on Wednesday and served it for a graduation party Saturday, and it still retained its moist texture and was a huge hit. Truly the best chocolate cake I’ve had.” ★★★★★

Chocolate Sheet Cake Ingredients & Substitutions

These are the main ingredients you need to make this moist chocolate sheet cake. You can find the full list of ingredients and measurements in the recipe card below.

Unsweetened cocoa powder — Dutch-process cocoa powder gives the chocolate sheet cake the richest, deepest chocolate flavor. I prefer it over natural cocoa powder in this recipe.

Leavening — you need both baking powder and baking soda for the cake to rise and have the proper texture. Chocolate cake is known for its open, spongy texture, and that mostly comes from the baking soda reacting with the acidity in buttermilk and sour cream. The baking powder helps the cake rise again in the hot oven for a flatter sheet cake.

Buttermilk and sour cream — these acidic ingredients tenderize the cake’s crumb so it’s unbelievably soft. The richness of the sour cream helps keep the cake moist for several days, too. If you don’t have a carton of buttermilk on hand, make your own buttermilk with my simple recipe.

Oil — a neutral-flavored oil, like vegetable oil, keeps the cake soft for days on end. Since this type of liquid oil doesn’t turn solid at room temperature or colder, the texture of the cake stays soft. I also use it in my chocolate cupcakes, so they last a long time!

Coffee or water — hot coffee deepens the flavor of the cocoa. Don’t worry, the cake won’t taste like coffee! You can use decaf coffee or boiling water instead if you prefer not to include any caffeine in your cake.

Powdered sugar — not only does powdered sugar sweeten the frosting, but it also adds structure by making the frosting sturdier for the perfect fluffiness. The sugar combines with the butter, making a stable network to hold the little pockets of air whipped into the mixture.

Milk or heavy cream — whole milk or heavy cream adds extra richness to the frosting and also helps to lighten it a bit, so it’s creamy and smooth.

Hot fudge sauce — hot fudge helps create a decadent, rich buttercream.

Can I use melted butter instead of oil?

Yes, it will taste delicious! Keep in mind that vegetable oil does help keep the cake soft and moist since it stays liquid at room temperature (or when chilled). Since the butter firms up as it cools, it will make the cake firmer.

My Secrets For The Best Chocolate Sheet Cake

I have 3 secret ingredients for the best chocolate sheet cake! The first is sour cream, which is also my secret weapon when making a classic layered chocolate cake. Not only does it add moisture and fat to the cake batter, making it extra flavorful and moist for days, its acidity also tenderizes the crumb so the cake is ultra-soft. The acid reduces gluten formation, so the cake isn’t tough.

Hot coffee amplifies the chocolate flavor in the cake. Think of it as a flavor booster! The cake needs moisture, so I like to add a liquid that will also enhance the cake, doing double duty. No, the cake won’t taste like coffee, but will rather have a deeper, more complex chocolatey flavor.

My last secret ingredient is hot fudge in the buttercream. (You can also use chocolate ganache.) Adding hot fudge sauce to the buttercream makes a luscious frosting with a more decadent chocolate flavor and a velvety texture.

Why Do You Add Hot Coffee After Mixing The Batter?

I know it might seem odd not to add it with the other wet ingredients, but by adding it at the end, the heat of the coffee helps to more rapidly hydrate the flour. So, when the cake goes into the oven, the flour is already absorbing liquid that may have otherwise evaporated in the high heat. This makes the cake bake up more moist and almost fudgy.

Pan Guide: Materials & Conversions

Use a lighter colored metal pan for the best chocolate sheet cake. Darker pans conduct more heat and can make the edges of the cake hard or burn. Glass or ceramic pans can work, but they insulate, so the cake may take a few minutes longer to bake and can make the outside soft and a bit sticky. If you decide to use a glass or ceramic baking dish, it’s best if you plan to serve the cake directly from the pan, and not to remove it before frosting, to prevent sticking.

To bake this cake in other pan sizes, here are the general conversions:

• 8″ rounds: Makes 3 layers; bake for about 30-35 minutes
• 9″ rounds: Makes 3 layers; bake for 25-30 minutes.
• 18×13″ rimmed baking sheet (half sheet pan): Makes a thin cake (like a Texas sheet cake) that can serve up to 36 people; bake for 15 to 20 minutes.
• Cupcakes: Makes 36 to 40; Fill each paper liner with 3 tablespoons of batter and bake for 18-20 minutes.

If you make a layer cake, check out my post on how to decorate a cake for simple tips on assembling and frosting the cake.

Pro Tips For Making This Recipe

Weigh the flour. For a cake that is perfectly moist and never dry, accurately measuring the flour is key! A kitchen scale is the best way to do this, but if you don’t have one, fluff your flour with a spoon, sprinkle it into your measuring cup, and use a knife to level it off. This prevents you from inadvertently overpacking the cup with flour.

If you want to remove the cake from the pan before frosting, line the pan with a parchment paper sling. Leave excess paper hanging over the two long sides of the pan so you can use it to lift the cooled cake out of the pan. Be careful when you remove it, though, as the cake is quite large and tender. If you want to serve it from the pan, you don’t need to line it!

You don’t need baking strips for this cake. I am a huge fan of baking round cake layers with water-soaked fabric baking strips so they bake up flat and even. (I have a whole post about how to bake flat cake layers if you choose round cake pans!) For sheet cakes, though, you have to attach two strips together, and it insulates the cake in an odd way, causing it to rise unevenly on the edge. Plus, since you aren’t stacking layers, it’s okay if the center domes a bit!

Allow the cake to cool completely before frosting. If it is still warm, the buttercream will melt into or slide off the cake. Let the cake come to room temperature before frosting.

How To Make A Chocolate Sheet Cake

Below, I’ve highlighted portions of the recipe in step-by-step process images along with instructions for making this easy chocolate sheet cake. You can find the full set of instructions in the recipe card below.

1. Sift together the all-purpose flour, sugar, cocoa powder, baking soda, baking powder, and salt into a large bowl, then whisk to combine. Set aside for now.

2. In a medium bowl, combine the sour cream, buttermilk, eggs, vegetable oil, and vanilla extract.

3. Slowly whisk the hot coffee or hot water into the rest of the wet ingredients. Then pour the wet mixture into the dry ingredients and whisk until no streaks of flour remain.

4. Pour the cake batter into a lightly greased 9×13-inch cake pan (lined with a parchment paper sling, if you want to remove the cake from the pan before serving). Bake the chocolate sheet cake at 350ºF for about 45 to 50 minutes. Allow the cake to cool completely in the pan.

5. Make the chocolate buttercream frosting in a large bowl or the bowl of a stand mixer using the paddle attachment. Beat the butter until smooth, then add the cocoa powder and salt. Slowly add in the powdered sugar and then pour in the hot fudge. Lastly, beat in enough whole milk or heavy cream so the frosting is smooth and spreadable.

6. To assemble the cake, you can remove it from the pan using the parchment paper sling. Spread the fudgy chocolate frosting all over the top of the cake. Decorate the chocolate sheet cake as you like (sprinkles are a great option for a birthday cake!), and serve!

5 from 314 votes

Chocolate Sheet Cake Recipe

Rich, moist Chocolate Sheet Cake is the perfect dessert for satisfying a large crowd. Top it with decadent chocolate buttercream for the ultimate indulgence.

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Course Dessert

Cuisine American

Prep Time 10 minutes minutes

Cook Time 50 minutes minutes

Cool Time 1 hour hour

Total Time 2 hours hours

Servings 15 to 20 servings

Calories 676kcal

Author John Kanell

Video

Equipment

• ▢
  Mixing Bowls
• ▢
  9×13-inch cake pan
• ▢
  Electric mixer

Ingredients

For the Cake:

• ▢ 3 cups all purpose flour (360g)
• ▢ 2⅔ cups granulated sugar (530g)
• ▢ ½ cup Dutch-process cocoa powder (50g)
• ▢ 2 teaspoons baking soda
• ▢ 1½ teaspoons baking powder
• ▢ ¾ teaspoon salt
• ▢ 1 cup whole or low-fat buttermilk room temperature (240ml)
• ▢ ½ cup sour cream room temperature (120g)
• ▢ 3 large eggs room temperature
• ▢ ¾ cup vegetable oil (180ml)
• ▢ 1 tablespoon vanilla extract
• ▢ 1½ cups hot coffee or boiling water (360ml)

For the Frosting:

• ▢ 1½ cup unsalted butter room temperature (340g)
• ▢ ¼ cup Dutch-process cocoa powder (25g)
• ▢ ¾ teaspoon salt
• ▢ 1 pound powdered sugar (450g)
• ▢ 1 to 3 tablespoons whole milk or heavy cream
• ▢ ⅓ cup hot fudge sauce or ganache (100g)
• ▢ Optional toppings (sprinkles, chopped nuts, shaved chocolate)

Instructions

For the Cake:

• Preheat the oven to 350ºF. Lightly grease a 9×13 inch cake pan with baking spray and line it with a parchment paper sling, if you plan on removing it from the pan.
• In a large bowl sift together the flour, sugar, cocoa powder, baking soda, baking powder and salt and whisk to combine.
• In a medium bowl, whisk together the sour cream, buttermilk, eggs, vegetable oil, and vanilla until combined. Slowly whisk in the hot coffee. Slowly pour the wet ingredients into the dry and whisk until no streaks of flour remain. Pour the batter into the prepared pan.
• Bake for about 45 to 50 minutes or until the center of the cake feels springy when gently pressed and the edges of the cake start to pull away from the pan. Allow the cake to cool completely in the pan.

For the Frosting:

• In a large bowl or the bowl of a stand mixer fitted with a paddle attachment, beat the butter on medium speed until smooth and creamy, about 2 minutes. Add in the cocoa powder and salt and mix on low speed until fully combined, stopping to scrape down the bowl as needed.
• With the mixer on low, gradually add in the powdered sugar ½ cup (60g) at a time. Stop and scrape down the bowl occasionally.
• Once all the powdered sugar has been incorporated, add in the fudge or ganache and mix on medium-low speed until well combined. Beat in enough milk or cream until the frosting is smooth, fluffy, and easily spreadable.

Assemble the Cake:

• Once the cake has fully cooled, you can remove the cake from the pan and discard the parchment paper if desired. Spread the buttercream on top of the cake. I like to make it swoopy using an offset spatula, but you can have fun with it! Decorate as desired with sprinkles, chopped toasted nuts, or shaved chocolate.

Notes

• Should the cake batter be thin? Yes! Chocolate cake is made with a fairly thin or liquid batter. It should be pourable, not thick enough to scoop or spread like my vanilla cake batter.
• The best doneness test for chocolate cake isn’t a toothpick! I prefer to test if a chocolate sheet cake is done by pressing the center with my finger. (A quick press is fast enough not to burn you!) If you poke it with a toothpick too soon, the cake can deflate and sink in the center. If you’re nervous about touching the cake, you can press it with the back of a small spoon or look for the visual sign that a small gap is forming between the edge of the cake and the sides of the pan.
• Party-Size Servings: This cake can easily be cut into bigger or smaller pieces. Cutting it into thirds, lengthwise, and fifths, crosswise, will make 15 generous servings. If you do fourths instead of thirds, you can get 20 servings. I have served this cake to up to 30 people before with thinner, rectangular pieces—it’s up to you and how big you want the slices!

Nutrition

Calories: 676kcal | Carbohydrates: 93g | Protein: 6g | Fat: 33g | Saturated Fat: 15g | Polyunsaturated Fat: 7g | Monounsaturated Fat: 8g | Trans Fat: 1g | Cholesterol: 87mg | Sodium: 489mg | Potassium: 178mg | Fiber: 2g | Sugar: 69g | Vitamin A: 672IU | Vitamin C: 0.2mg | Calcium: 75mg | Iron: 2mg

*Nutrition Disclaimer

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Storage & Make-Ahead Tips

Storing: Store the chocolate sheet cake in an airtight container at room temperature for up to 5 days.

Freezing: If you know beforehand that you will be freezing the cake, freeze it unfrosted for ease. Once completely cool, wrap it with plastic wrap and aluminum foil and freeze. You can also freeze the frosted cake in the same way, but the frosting tends to stick to the plastic wrap. No matter which option you choose, freeze the chocolate sheet cake for a maximum of 1 month, or the cake can dry out.

Make-ahead: Since the cake itself lasts for so many days and stays soft, you can make it a day or so in advance. You can also make the frosting 2 days in advance and store it in the fridge in an airtight container. Bring the frosting to room temperature, then beat it again until light and fluffy before frosting the cake.

FAQs and Troubleshooting

More Cake Recipes To Try

German chocolate cake is a rich 3-layer cake with an unforgettable coconut pecan frosting. It’s a great cake for any occasion!

Fudgy and moist, my devil’s food cake is absolutely irresistible! Like this chocolate sheet cake, I use coffee to amplify the chocolate flavor.

Thanks to zucchini, this chocolate zucchini cake is unbelievably moist (and don’t worry, you can’t taste even a hint of vegetables in this cake!). I love making this cake in the summer, when zucchini is abundant.

Chocolate and berries are a hard combo to beat, and my chocolate raspberry cake is no exception! Decadent chocolate cake is balanced beautifully with zingy raspberries.

Speaking of winning combinations, this chocolate peanut butter cake combines another satisfying pair. I love decorating the cake with halved peanut butter cups.

If you’ve tried this chocolate sheet cake recipe, then don’t forget to rate it and let me know how you got on in the comments below. I love hearing from you!