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Homemade Chocolate Brownie Cake Recipe

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This homemade Chocolate Brownie Cake recipe creates a delicious hybrid of chocolate brownies and a Texas sheet cake. The cake is topped with luscious chocolate icing made from scratch.

Sliced chocolate brownie cake and a metal spatula.

Most brownie recipes only make an 8×8 or 9×9 batch. I came up with this Homemade Chocolate Brownie Cake in order to make a larger batch.

I combined some elements of a few recipes, tweaked them a little, and bam! These chocolate brownies are what some may call a Brownie Sheet Cake.

Mound of cocoa powder and sugar on a white background.

Ingredients

To make a 9×13 pan of chocolate brownie cake from scratch, you need the following ingredients:

Chocolate Syrup

  • ¼ cup unsweetened cocoa powder
  • ½ cup water
  • 1 cup sugar
  • 1 teaspoon vanilla
  • ¼ teaspoon salt

Brownie Cake Batter

  • 1½ cups all-purpose flour
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • 2 tablespoons espresso powder
  • 10 tablespoons butter (= 1 stick + 2 tablespoons)
  • ¾ cup baking cocoa
  • ¼ cup vegetable oil
  • 2 cups sugar
  • 4 large eggs
  • 2 teaspoons vanilla extract
  • ⅔ cup chocolate chips
  • Chocolate Syrup

Chocolate Icing

  • 1¼ cups chocolate chips
  • 3 tablespoons corn syrup
  • 1 stick butter

How To Make a Chocolate Brownie Cake

Start by making a simple chocolate syrup. Just sugar, cocoa, water, vanilla, and a little salt.

Boiling chocolate in a small saucepan.

The reason to make the syrup first is that it has to come to a boil and then cool. It will thicken some during the cooling period.

While the syrup is cooling, start the other aspects of the brownies, like preparing a 9×13 pan. I like to line it with aluminum foil sprayed with non-stick spray.

All-purpose flour and espresso in a glass bowl.

Next, gather the other ingredients together. (Above is flour, baking powder, salt, and espresso powder.)

Eggs in a small glass bowl.

It’s best to add eggs one at a time. I like to crack all of mine into a little glass bowl before adding them. You never know when you will run across a bad egg.

Now, microwave the butter until melted in a medium-size glass bowl. Add cocoa and oil and whisk until smooth.

Transfer the cocoa mixture to a bowl of an electric mixer. Stir in the sugar and add eggs, one at a time, mixing well after each addition. Add vanilla.

Gradually add the flour mixture. Pour in chocolate syrup and chocolate chips.

Brownie batter on a whisk attachment in a mixing bowl.

Baking Time

Pour batter into prepared 13×9 pan and bake for 25-30 minutes or until done. Let cool before icing.

Baked brownie cake without icing.

This is how it looks before the icing is added.

Chocolate chips in a glass bowl with a stick of butter.

The icing is a simple chocolate glaze made with chocolate chips, butter, and a little corn syrup.

To make the icing, melt chocolate chips and butter together in a microwave-safe bowl in 30-second intervals on high, stirring well after each segment. (It took me a total of one minute + an additional 10 seconds.)

Add corn syrup and stir until smooth. Let sit for 5 minutes before pouring over brownies.

Sliced chocolate brownie cake and a metal spatula.

Chocolate Brownie Cake

4.60 from 49 votes
Chocolate Brownie Cake – this dessert recipe is so good. It's a mix between a brownie and chocolate sheet cake. Yum!
Prep Time 15 minutes
Cook Time 40 minutes
Total Time 55 minutes
Servings: 16 slices
Course: Desserts
Cuisine: American
Calories: 492

Ingredients
  

Chocolate Syrup
  • ¼ cup unsweetened cocoa powder
  • ½ cup water
  • 1 cup sugar
  • 1 teaspoon vanilla
  • ¼ teaspoon salt
Brownie Batter
  • cups all-purpose flour
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • 2 tabelspoons espresso powder
  • 10 Tablespoons butter (1 stick + 2 tablespoons)
  • ¾ cup baking cocoa
  • ¼ cup vegetable oil
  • 2 cups sugar
  • 4 large eggs
  • 2 teaspoons vanilla extract
  • cups chocolate chips
  • Chocolate Syrup
Chocolate Icing
  • cups chocolate chips
  • 3 tablespoons corn syrup
  • ½ cup butter (1 stick)

Method
 

  1. To make the syrup: in a medium or large saucepan, whisk the cocoa powder and sugar until well blended. Add water and whisk over medium-high until it starts to boil and becomes a little frothy. Continue boiling for approximately 3 minutes. Reduce heat and allow to simmer for 2 more minutes. Remove from the heat and add salt. Let cool.
  2. Preheat oven to 350 degrees. Line bottom of 13×9 pan with aluminum foil and spray with non-stick cooking spray.
  3. Combine flour, baking powder, salt, and espresso powder and set aside.
  4. Microwave butter until melted in a medium size glass bowl. Add cocoa and oil and whisk until smooth.
  5. Transfer cocoa mixture to a bowl of an electric mixer. Stir in sugar. Add eggs, one at a time, mixing well after each addition. Add vanilla. Gradually add flour mixture. Pour in chocolate syrup and chocolate chips.
  6. Pour batter into prepared 13×9 pan and bake for 25-30 minutes or until done. Let cool before icing.
  7. To make the icing: Melt chocolate chips and butter together in a microwave-safe bowl in 30 second intervals on high, stirring well after each segment. (It took me a total of one minute + an additional 10 seconds.) Add corn syrup and stir until smooth. Let sit for 5 minutes before pouring over brownies.

Nutrition

Serving: 1sliceCalories: 492kcalCarbohydrates: 68gProtein: 5gFat: 24gSaturated Fat: 13gPolyunsaturated Fat: 10gTrans Fat: 1gCholesterol: 81mgSodium: 340mgFiber: 3gSugar: 53g

Video

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Let us know how it was!
Iced brownie cake in a foil lined baking pan.

Like chocolate? Be sure to check out these other delicious chocolatey desserts:

78 Comments

  1. OMG! This looks utterly amazing! My son makes something similar but I think he needs to add the syrup. I’m going to show him this.

    Happy SITS Saturday Sharefest!

  2. 5 stars
    You had me at brownie but then you took it over the top! I might do this for my little guys 2nd birthday! Great idea. Thanks for sharing.

4.60 from 49 votes (43 ratings without comment)

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