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Homemade Chocolate Blackout Sheet Cake with Chocolate Cookie Crumbs photo

Chocolate Blackout Sheet Cake with Chocolate Cookie Crumbs

This Chocolate Blackout Sheet Cake is a chocolate lover’s dream! Indulge in rich layers topped with velvety ganache and crunchy cookie crumbs.
Print Recipe Pin Recipe
Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

Chocolate Cookie Crumbs
  • 1 cup all-purpose flour
  • 65 g Dutch-process cocoa powder sifted
  • 100 g granulated sugar
  • 1 teaspoon cornstarch
  • 1 teaspoon kosher salt
  • 6 tablespoons unsalted butter melted
Chocolate Cake
  • 1 ½ cups all-purpose flour
  • 75 g Dutch-process cocoa powder sifted
  • 2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1 teaspoon kosher salt
  • 1 ½ cups granulated sugar
  • 1 cup low-fat buttermilk
  • ¾ cup vegetable oil
  • 2 large eggs at room temperature
  • 2 teaspoons vanilla extract
Chocolate Ganache
  • 1 cup heavy cream
  • 3 tablespoons unsalted butter cut into chunks
  • 100 g granulated sugar
  • 2 tablespoons light corn syrup or golden syrup
  • 1 teaspoon vanilla extract
  • 60 g dark chocolate chips or chopped dark chocolate
  • 50 g Dutch-process cocoa powder sifted
  • 1 pinch salt
Optional Decoration
  • Sprinkles

Equipment

  • Mixing bowls
  • Whisk
  • Rubber spatula
  • 9x13 inch baking pan
  • Cooling rack
  • Double boiler or microwave-safe bowl

Method
 

Directions
  1. Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan to ensure your cake releases easily after baking.
  2. In a mixing bowl, combine 1 cup of all-purpose flour, 65g of sifted Dutch-process cocoa powder, 100g of granulated sugar, 1 teaspoon of cornstarch, and 1 teaspoon of kosher salt. Mix well. Pour in 6 tablespoons of melted unsalted butter and stir until the mixture resembles wet sand. Set aside.
  3. In another large mixing bowl, whisk together 1 ½ cups of all-purpose flour, 75g of sifted Dutch-process cocoa powder, 2 teaspoons of baking soda, 1 teaspoon of baking powder, and 1 teaspoon of kosher salt. In a separate bowl, mix 1 ½ cups of granulated sugar, 1 cup of low-fat buttermilk, ¾ cup of vegetable oil, 2 large eggs, and 2 teaspoons of vanilla extract until smooth. Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
  4. Pour half of the chocolate cake batter into the prepared baking pan. Sprinkle half of the chocolate cookie crumb mixture over the batter, then add the remaining batter on top. Finish by sprinkling the rest of the cookie crumbs over the top layer.
  5. Bake in the preheated oven for 30-35 minutes or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.
  6. In a double boiler or microwave-safe bowl, heat 1 cup of heavy cream until just simmering. Remove from heat and add 3 tablespoons of unsalted butter, 100g of granulated sugar, 2 tablespoons of light corn syrup, and 1 teaspoon of vanilla extract. Whisk until the butter melts and the mixture is smooth. Stir in 60g of dark chocolate until melted and combined, then sift in 50g of Dutch-process cocoa powder and a pinch of salt. Mix until smooth.
  7. Once the cake has cooled completely, pour the chocolate ganache over the top, allowing it to drip down the sides. Use an offset spatula to spread it evenly across the surface.
  8. If desired, sprinkle with colorful sprinkles for a festive touch.

Notes

  • This cake can be frozen for up to 3 months. Thaw in the fridge overnight before serving.
  • For a less sweet cake, reduce the sugar in the batter or ganache.
  • Customize with seasonal toppings like fruit or flavored extracts.