Blackberry Blackout Cake

Blackberry Blackout Cake
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I know I’ve mentioned this before but I’m not much of a Halloween person. It’s not that I dislike the holiday. I kind of enjoy the energy of the day in general. It’s just that I don’t have many ideas surrounding it. I’m hopeless when it comes to costume concepts, I can’t plan a Halloween party and make it somehow different from a regular party, and I have next to no recipe ideas. Spooky treats are the furthest thing from my mind it seems. So today’s Blackberry Blackout Cake is more of an attempt at a Halloween-friendly dessert. How successful I was is really up to you. But I can assure you this cake is very delicious, very chocolatey, and gorgeously balanced. So while this may not be a Halloween cake, it is at least a delightful cake. 

Ingredients for the Blackberry Blackout Cake

When I set out on this cake experiment, I had a hunch that if I coated the outside of a nearly jet-black cake with blackberries, it might look like a brain. And naturally, the thought of a brain led me to zombies, which led to me Halloween. Now, I’m not one for kitschy Halloween. I don’t have kids, so it’s maybe a little weird for me to affix googly eyes to a brownie. So I generally try for a classy Halloween treat. And what’s classier than fresh fruit?

Melting the chocolate, milk, and cocoa powder together using a double boiler
Sifting cake flour into a bowl

I then thought I would make the berries look gooey and squidgy by dusting them with an iridescent luster. Well, I think it’s safe to say I fell a little short in terms of appearance. It’s not particularly brain-like at all. I only pushed ahead with the concept because it turns out a berry-coated chocolate cake is a very delicious thing. But before I get to that, let’s talk about what this Blackberry Blackout Cake actually is. 

Adding eggs to the creamed butter and sugar

This cake features layers of rich dark chocolate cake enrobed in a glossy chocolate ganache frosting coated with plump blackberries dusted with luster powder. Each component of this cake is straightforward to put together, but you will have to bust out a double boiler a few times. Let’s start by tackling the cake.

Folding the chocolate mixture into the egg mixture

Now, this blackout cake starts as all good layer cakes do, by greasing a few cake pans and lining them with parchment paper. I know it’s a bit of a pain to cut out circles of parchment for the bottom of each cake pan, but if you’ve ever had a cake snag, rip, and fall apart on its way out of a pan, you know what a vital role the parchment plays. So grab the scissors and guard yourself against cake-related disappointment down the road. 

Stacking and frosting the cake

Once the pans are prepped, assemble a double boiler. Now, you can buy a double boiler, but I have to be honest, I don’t know why you would. It’s very easy to DIY it. All you need is a heat-proof bowl and a small saucepan. When selecting the tools for the job be sure to select a bowl that will fit snuggly in the mouth of the pot but not touch the bottom. Once you’ve found the appropriate pot and bowl, fill the saucepan with 2-3 inches of water and bring it to a boil and reduce it to a simmer. Place your ingredients in the bowl and fit the bowl over the pot. In this case, you’ll be adding chocolate chips, black cocoa powder, milk, and sour cream.

Decorating the cake with blackberries

Once a smooth glossy mixture has formed, take it off of the heat and set it aside to cool slightly. We don’t want the hot chocolate to cook the eggs we’re going to put in the cake before the oven has a chance to. That’s why I like to tackle the chocolate portion of the cake first. Next, we’re going to sift the dry ingredients together and set them aside. In another bowl cream the butter and sugar together before beating the eggs in individually. Yes, this Blackberry Blackout Cake uses quite a few bowls, three in total, in fact. But I promise it’s for a good cause.

Blackberry Blackout Cake

Now, all that’s left is to add the chocolate to the egg mixture before adding the dry ingredients. And there you have it, cake batter so good you’ll struggle not to eat it directly from the bowl. Fill your prepared cake pans with about 400g of the batter and smooth the tops, using an offset spatula. Bake the cakes for 50 minutes, rotating the pans once halfway through. Set the cakes aside to cool. While the cake is cooling, you can get the frosting underway. This cake positively sings when paired with a rich chocolate ganache frosting. So while it may be tempting to default to your go-to favorite, trust me and give this one a try.

Blackberry Blackout Cake

This frosting starts as the cake did with a double boiler. This time we’re melting chocolate chips into some cream with honey and black cocoa powder. Once the mixture is smooth and glossy, stir in some sour cream. I love the sour cream here. It gives the frosting a refreshing tang and keeps it from being overwhelmingly rich. Now, set the frosting aside to solidify. As with any ganache, the frosting will thicken and become spreadable after sitting for an hour or so. But don’t leave it too long or it will be too stiff to frost with. I prefer to hurry the process along by popping the frosting into the fridge for 15-20 minutes. I find it reaches the perfect consistency when I do this.

Blackberry Blackout Cake

From here, it’s as simple as leveling, stacking, and frosting the cakes. And once that is done, you can coat the outside of the cake with blackberries. Or not. It takes quite a few blackberries to cover the cake completely, so you could add half of that and still have all the flavourful benefits of the blackberries with much less work. It does, as it turns out, take time to coat an entire cake in berries, who knew?

So that’s everything you need to know about this Blackberry Blackout Cake. It’s rich, chocolaty, and decidedly moody. And it’s apparently the most Halloweeny thing I’m capable of dreaming up. I hope you all have a wonderfully spooky evening!


Blackberry Blackout Cake

Blackberry Blackout Cake

This Blackberry Blackout Cake features layers of dark chocolate cake enrobed in a glossy chocolate ganache frosting coated in fresh blackberries.
Prep Time 1 hour
Cook Time 1 hour 10 minutes
Chilling Time 2 hours
Course Dessert
Servings 8


  • 3 6" cake pans
  • 1 stand mixer or hand mixer
  • 1 small saucepan
  • 1 heatproof bowl


Blackout Cake

  • 56g (2oz) semi-sweet chocolate chips
  • ½ cup black cocoa powder **
  • ½ cup milk I used 2%
  • ¼ cup sour cream
  • 2 cups cake flour
  • 1 tsp baking powder
  • 1 tsp baking soda
  • 1 tsp kosher salt
  • 1 cup unsalted butter room temperature
  • 1⅓ cup granulated sugar
  • 4 large eggs
  • 2 tsp vanilla extract

Chocolate Ganache Frosting

  • 200g (7oz) semi-sweet chocolate chips
  • ½ cup heavy cream
  • 2 tbsp honey
  • 2 tbsp black cocoa powder
  • cup sour cream


  • 1.1 kg (2.5 lbs) fresh blackberries ***
  • iridescent luster dust optional


  • Preheat the oven to 350°F. Grease and line 3 6-inch cake pans with parchment paper. Set them aside.
  • Place the chocolate chips, milk, and sour cream in a heat-proof bowl. Sift the cocoa powder into the bowl and set it aside.
    56g (2oz) semi-sweet chocolate chips, ½ cup milk, ¼ cup sour cream, ½ cup black cocoa powder **
  • Place a small saucepan fill with 3-inches of water over high heat. Bring the water to a boil and reduce it to a simmer. Place the heat-proof bowl over the mouth of the pot and stir until the chocolate melts and all the ingredients are thoroughly integrated. Take the mixture off of the heat and set it aside to cool.
  • While the chocolate is cooling, sift the flour, baking powder, and soda into a medium-sized bowl. Add the salt and whisk to combine. Set it aside.
    2 cups cake flour, 1 tsp baking powder, 1 tsp baking soda, 1 tsp kosher salt
  • In the bowl of a stand mixer fitted with a paddle attachment place the butter and sugar. **** Cream the sugar into the butter until light and fluffy. Add the eggs to the mixture one at a time, scraping down the sides of the bowl as needed. Add the vanilla and mix until fully integrated.
    1 cup unsalted butter, 1⅓ cup granulated sugar, 4 large eggs, 2 tsp vanilla extract
  • Pour the chocolate mixture into the egg mixture and mix until uniform. Add half of the flour mixture and mix until no streaks remain. Repeat with the remaining flour mixture.
  • Fill the prepared pans with the cake batter. Add roughly 400g of batter to each pan. Smooth tops with an offset spatula and transfer the cake to the oven. Bake for 50 minutes, rotating the pans once halfway through.
  • Take the cakes out of the oven and remove them from their pans. Place the cakes on a cooling rack and set them aside to cool for two hours.

For the Ganache

  • While the cakes are cooling, make the ganache. Place the chocolate, cream, and honey in a heat-proof bowl. Sift in the black cocoa powder and set it aside.
    200g (7oz) semi-sweet chocolate chips, ½ cup heavy cream, 2 tbsp honey, 2 tbsp black cocoa powder
  • Once again, bring a small saucepan filled with 2-3 inches of water up to a boil before reducing it to a simmer. Place the heat-proof bowl over the mouth of the pot and stir until the chocolate melts and all the ingredients are thoroughly integrated.
  • Take the chocolate mixture off of the heat and whisk in the sour cream. Transfer the ganache to the fridge and chill for 15-20 minutes before frosting.
    ⅓ cup sour cream

To Assemble

  • Level the cakes and place one layer, cut side up on a turntable. Spread a little ganache on top of the layer and place a second cake layer on top. Repeat.
  • Once the third cake layer is in place, coat the cake evenly with the remaining ganache. Cover the cake with the blackberries and dust the berries with luster, if using. Chill the cake for an hour prior to serving.
    1.1 kg (2.5 lbs) fresh blackberries ***, iridescent luster dust


** If you can’t find black cocoa powder, just use regular Dutch-processed cocoa powder. The black simply makes the cake darker, that’s all.  
*** This is roughly how many berries you will need to fully encase the cake. You can reduce the number of berries significantly if you just want to use them as a garnish. 
**** You can also use a large bowl and a hand mixer for this.
Keyword blackberries, chocolate cake, dark chocolate, ganache

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