Serving a slice of Blackout Chocolate Cake.

Chocolate Blackout Cake

  • Author: Rebecca Blackwell
  • Total Time: 2 hours
  • Yield: 16 slices


  • Three 8-inch layers Devil’s Food Cake (*see note)
  • 5 ounces bittersweet chocolate, chopped into small pieces
  • 1½ tsp unflavored gelatin
  • 3 tsp cold water
  • 2 cups whole milk
  • ½ cup granulated sugar
  • ¼ tsp salt
  • 6 large egg yolks
  • 4 tbsp cornstarch
  • 2 tsp pure vanilla extract
  • 24 ounces heavy whipping cream, divided (3 cups)
  • 20 ounces semi-sweet or bittersweet chocolate, chopped into small pieces


Make the Chocolate Pastry Cream:

  1. Put the 5 ounces of bittersweet chocolate into a medium size bowl and set on the counter near your stovetop.
  2. In a small dish, stir the gelatin and water together to combine. There should be just enough water to moisten the gelatin, creating a thick paste. Set aside.
  3. Add milk, sugar, salt, egg yolks and cornstarch to a 4-quart or larger heavy bottomed saucepan and whisk vigorously to combine. Bring to a boil over medium heat, whisking constantly, at which point the mixture will have thickened to the point that the whisk will leave tracks as you stir. Remove from the heat and whisk vigorously for 30 seconds longer.
  4. Pour the cream into the bowl with the chocolate, so that it covers the chocolate. Break the gelatin into small pieces and drop them into the hot pastry cream. Let stand for 3 or 4 minutes to allow the chocolate to melt.
  5. Stir the cream until the gelatin and chocolate are completely incorporated, about 20 seconds. Whisk in vanilla. Cover with plastic wrap, pressing the wrap over the surface of the pastry cream. Refrigerate for at least 3 hours and up to 3 days.
  6. Using an electric mixer, whip 1/2 cup (4 ounces) heavy cream until medium peaks form. Add the cooled pastry cream and beat it into the whipped cream on medium speed until fully incorporated and smooth.

Make the Chocolate Ganache:

  1. Put the 20 ounces of chopped bittersweet or semisweet chocolate into a medium size bowl.
  2. Heat 20 ounces of cream in a saucepan or in the microwave until small bubbles start to appear around the edges. Pour the hot cream over the chocolate and let stand for 5 minutes. Stir until the chocolate and cream are completely blended.
  3. Put the ganache in the refrigerator, uncovered, to let it cool until it’s thick enough to spread over your cake. This should take roughly 30 minutes. Stir the ganache every once in a while, keeping an eye on its consistency. If the ganache gets too stiff to spread, set the bowl over a pan of gently simmering water and stir just until the bottom of the ganache begins to melt. Remove from the simmering water and stir. Repeat this process as necessary to achieve the right consistency.

Assemble the Chocolate Blackout Cake:

  1. Place one layer of Devil’s Food Cake onto a serving platter or cake plate. Spread the cake with 1/2 of the chocolate pastry cream, spreading the cream to within a half inch of the edges of the cake. Top with a second layer of Devil’s Food Cake. Spread the second layer with the remaining pastry cream and top with the third layer of cake.
  2. Use an icing spatula to spread the chocolate ganache over the top and sides of the cake.


  • Pro tip! Devil’s Food Cake has a very tender crumb – a quality that makes it meltingly delicious, but can also makes stacking three layers a bit challenging. Freezing the cake layers for at least 1 hour (and up to 3 months) makes assembling the layers much easier. If your cake layers have been frozen for more than 1 hour, let the assembled cake sit out at room temperature for 3-4 hours to thaw before serving. After letting the cake thaw at room temperature, refrigerate the cake if you’re not serving it right away.