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Old-Fashioned Chocolate Brownie Cake

This easy chocolate brownie cake is an old-fashioned recipe that gives you the the taste of chocolate walnut brownies in sheet cake form. Just like grandma used to make!

Prep Time
10 mins
Cook Time
10 mins
Total Time
30 mins
Servings: 20 squares
Calories: 325 kcal
Course: Dessert
Cuisine: American

Ingredients

Brownie Cake
  • 2 cups flour
  • 2 cups sugar
  • ¾ cup butter
  • 2 TBS cocoa powder
  • 1 cup water
  • ½ cup buttermilk
  • 2 eggs
  • 1 tsp baking soda
  • 1 tsp vanilla
  • ½ tsp salt
  • 1 cup chopped walnuts optional garnish
Icing
  • ½ cup butter
  • 1 TBS cocoa
  • 6 TBS milk
  • 2 cups powdered sugar

Instructions

Brownie Cake
    Cup of Yum
  1. Preheat your oven to 400 degrees and grease a large baking sheet.
  2. Mix the flour, salt, baking soda, and sugar in a large bowl and set aside.
  3. Heat a saucepan over medium-high heat on the stove. Melt butter in pot.
  4. Once melted, add the cocoa powder and water and bring the mixture to a boil.
  5. Once boiling remove from heat and add the boiling chocolate mixture to the flour mixture from earlier and stir until well combined.
  6. Add buttermilk, eggs, and vanilla to the mixture and combine until you have a nice smooth batter. This can be done by hand or with a hand mixer.
  7. Pour the batter into the prepped baking sheet making sure to evenly spread it across the entire sheet pan.
  8. Bake cake in the oven for 20-22 minutes or until cake is cooked all the way through.
  9. While the cake is baking, make the icing according to the instructions below.
  10. Top the cake with icing within five minutes of removing the cake from the oven.
  11. Top with chopped walnuts if desired.
  12. Allow cake to cool completely then cut into squares and serve.
Icing
  1. In a medium, heat-safe bowl, measure out powdered sugar and set aside for later.
  2. Heat a pot over medium-high heat on the stove. Melt butter in pot.
  3. Add cocoa and milk to melted butter and bring to a boil.
  4. Put your powdered sugar into a small bowl then pour the boiled mixture over the powdered sugar and stir to combine to make your icing.

Notes

  • Add the walnuts immediately after adding the icing rather than waiting until it hardens. This will keep the nuts from falling off when you slice the cake.
  • Use a spatula to make sure that the chocolate brownie cake batter spreads around the entire sheet pan in one even layer.
  • Leave the chocolate brownie cake in the pan rather than slicing it all and removing for storage. I recommend just covering it with something like this sheet pan lid.
  • Remove the chocolate mixtures from heat as soon as they start boiling, don’t let them keep boiling or you’ll lose some of the moisture in the cake and icing.
  • Use a small rectangle spatula to remove the cake squares from the pan without destroying the rest of the squares.

Nutrition Information

Serving 1square Calories 325kcal (16%) Carbohydrates 43g (14%) Protein 3g (6%) Fat 16g (25%) Saturated Fat 8g (40%) Cholesterol 48mg (16%) Sodium 230mg (10%) Potassium 73mg (2%) Fiber 1g (4%) Sugar 32g (64%) Vitamin A 395IU (8%) Vitamin C 1mg (1%) Calcium 26mg (3%) Iron 1mg (6%)

Nutrition Facts

Serving: 20squares

Amount Per Serving

Calories 325

% Daily Value*

Serving 1square
Calories 325kcal 16%
Carbohydrates 43g 14%
Protein 3g 6%
Fat 16g 25%
Saturated Fat 8g 40%
Cholesterol 48mg 16%
Sodium 230mg 10%
Potassium 73mg 2%
Fiber 1g 4%
Sugar 32g 64%
Vitamin A 395IU 8%
Vitamin C 1mg 1%
Calcium 26mg 3%
Iron 1mg 6%

* Percent Daily Values are based on a 2,000 calorie diet.