Dark Chocolate Sheet Cake with Chocolate Buttercream

Chocolate dreams are made of dark chocolate sheet cake! This easy chocolate cake recipe comes together in minutes and bakes up into a perfectly moist Devil’s food chocolate cake topped with swirls of chocolate buttercream frosting! Recipe makes 12 to 15 servings.

Dark Chocolate Sheet Cake

Perfect for birthdays, parties, and any day that calls for chocolate, you’ll love this rich and decadent chocolate sheet cake.

Best of all, this recipe is simple and foolproof! The stir together cake batter comes together quickly using one large bowl and a whisk. You’ll also need a stand mixer fitted with the paddle attachment to make the chocolate frosting.

Dark Chocolate Sheet Cake

The Best Dark Chocolate Sheet Cake

Cocoa Powder – You’ll use unsweetened cocoa powder in both the cake and the frosting. I like Dutch-processed baking cocoa (with higher levels of cocoa butter) for maximum chocolate flavor.

Dutch process cocoa has a more intense chocolate flavor and results in a darker, fudgier chocolate cake than natural unsweetened cocoa powder. I use and recommend Rodelle Gourmet Baking Cocoa.

Chocolate – This recipe uses 4 ounces semisweet chocolate in the cake. Use a high quality semisweet chocolate baking bar (Ghirardelli is my fave!) and finely chop the chocolate with a serrated knife.

Instant Espresso – Chocolate and espresso are made for each other, and a touch of instant espresso adds depth to the chocolate cake (if you’re not a coffee lover, feel free to omit the espresso).

Room Temperature Ingredients – Room temperature eggs, milk, and Greek yogurt (or sour cream) incorporate easily into the batter and ensure an extra moist chocolate sheet cake.

Boiling Water – My favorite chocolate cake recipes all include boiling water. Boiling water whisked into the batter blooms and dissolves the cocoa for a super rich, Devil’s food chocolate flavor.

Bake Time – Bake cake until the top springs back to the touch and a tester inserted in the center come out with a few crumbs attached, about 24 to 26 minutes.

Frost Cake – Use an offset spatula to swirl chocolate buttercream over the cake. If desired, sprinkle flaky sea salt or sprinkles over the frosting. Chill the frosted cake for 20 minutes before slicing into squares with a sharp knife.

Perfect Chocolate Buttercream Frosting

Chocolate buttercream frosting is the best frosting for dark chocolate cake and so easy to make from scratch!

  1. Beat room temperature butter and salt together until softened and combined. Gradually add sifted cocoa to the mixer bowl, beating until incorporated.
  2. Mix in vanilla, then add powdered sugar 1 cup at a time, alternating with 1 tablespoon of heavy cream. Use a spatula to scrape down the bowl as needed.
  3. Add remaining 2 tablespoons of heavy cream and mix on low speed until combined, then beat on medium speed for 1 to 2 minutes, until frosting is light and airy.
Dark Chocolate Sheet Cake

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Dark Chocolate Sheet Cake

Dark Chocolate Sheet Cake with Chocolate Buttercream

  • Author: Laura Kasavan
  • Prep Time: 35 minutes
  • Cook Time: 25 minutes
  • Total Time: 1 hour
  • Yield: 12 to 15 servings
  • Category: Dessert
  • Method: Bake
  • Cuisine: American
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Description

Rich and decadent dark chocolate sheet cake topped with perfect chocolate buttercream frosting makes the best chocolate cake! Recipe makes 12 to 15 servings.


Ingredients

Cake

  • 1 1/2 cups all-purpose flour
  • 3/4 cup Dutch process unsweetened cocoa
  • 1 1/2 tsp baking powder
  • 1/2 tsp baking soda
  • 1/2 tsp salt
  • 1 cup granulated sugar
  • 1/2 cup light brown sugar
  • 2 large eggs plus 1 egg yolk, at room temperature
  • 1/2 cup milk, at room temperature
  • 1/2 cup plain fat-free Greek yogurt, at room temperature
  • 1/2 cup vegetable or canola oil
  • 2 tsp vanilla extract
  • 2 tsp instant espresso
  • 1/2 cup boiling water
  • 4 oz semisweet chocolate, finely chopped

Chocolate Buttercream Frosting

  • 1 cup unsalted butter, softened
  • 1/2 tsp salt
  • 3/4 cup Dutch process unsweetened cocoa, sifted
  • 2 tsp vanilla extract
  • 2 1/2 cups powdered sugar
  • 5 Tbsp heavy cream

Instructions

  1. Preheat oven to 350°F and spray a 13 x 9-inch baking pan with nonstick spray.
  2. Make cake: Whisk together flour, cocoa, baking powder, baking soda, and salt in a large bowl; make a well in the center of the mixture. Add sugars, eggs, egg yolk, milk, yogurt, oil, and vanilla to flour mixture; whisk in just until incorporated. Dissolve instant espresso in boiling water; add to batter and whisk in just until smooth. Fold in chopped chocolate.
  3. Pour cake batter into prepared baking pan and smooth with an offset spatula; tap pan sharply to reduce air bubbles.
  4. Bake cake for 24 to 26 minutes, until top springs back to the touch, a toothpick inserted in the center comes out with a few crumbs, and the edges are pulling slightly away from the pan. Let cool completely in pan on a wire rack.
  5. Make frosting: Beat butter and salt in a large mixer bowl on medium speed until combined. With the mixer on low speed, gradually add sifted cocoa, beating until incorporated. Mix in vanilla. Add powered sugar 1 cup at a time, alternating with 1 tablespoon of heavy cream. Scrape down the bowl as needed. Add remaining 2 tablespoons of heavy cream and mix on low speed until combined, then beat on medium speed for 1 minute, until light and airy.
  6. Dollop frosting over cooled cake and swirl with an offset spatula. Chill cake for 20 minutes in the refrigerator before slicing.
  7. Store leftovers tightly covered overnight at room temperature, or in an airtight container in the refrigerator up to 3 days (bring to room temperature before serving).

Notes

Cocoa: Dutch process cocoa has a more intense chocolate flavor and results in a darker, fudgier chocolate cake than natural unsweetened cocoa powder. I use and highly recommend Rodelle Gourmet Baking Cocoa.

Instant espresso: I recommend Starbucks VIA

Keywords: Chocolate Sheet Cake, Chocolate Cake, Chocolate, Chocolate Buttercream Frosting, Chocolate Frosting

Dark Chocolate Sheet Cake

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48 Comments

    1. Hi Cal, you can use natural cocoa powder instead. Just keep in mind that the cake will be less rich and fudgy because Dutch process cocoa has higher levels of cocoa butter.

  1. This looks so delicious! I don’t have any expresso instant coffee can you suggest a substitute? I only use a Keurig . Also can sour cream be substituted for the Greek yogurt?

    1. Hi Irma, yes you can use sour cream, and you can use 1/2 cup hot coffee (or 1/2 cup hot brewed espresso) instead of the instant espresso + hot water.

  2. Thank you for the recipe, this cake turned out perfectly and so delicious! I used a 1/2 cup French pressed coffee instead of instant espresso.

    1. Hi Kate, I use instant espresso granules (usually Starbucks Via). You can also use 1/2 cup brewed espresso. Happy baking!

  3. The batter tastes marvelous but uh oh….it’s in the oven and I left out the 1/2 cup of light brown sugar. It’s for a party. What do you think will happen?

    1. Hi Elizabeth, you’ll notice the difference most likely in the texture (the cake may be a touch less moist, though you should be fine because of the oil, extra egg yolk, and Greek yogurt). If you see this and can check the bake time on the early side (after 24 minutes), I suggest that too. Once you add the frosting, everything should be fine. Hope that helps! 🙂