Decadent Dark Chocolate and Custard Nanaimo Bar Cake
Nanaimo Bar Cake – the most delicious chocolate cake layers baked on a graham cracker, almond, coconut, and chocolate crust, with a custard filing and covered in a chocolate fudge buttercream.
Nanaimo Bars
If you caught my last post, Nanaimo Bars , you learned that this delicious, Canadian, no-bake dessert is a breeze to whip up and a dream to eat! With the graham cracker, coconut, almond and chocolate crust, paired with a custard filling and chocolate ganache, it’s incredibly decadent. When I finally made my own batch of Nanaimo Bars, I knew I also needed to make a Nanaimo Bar Cake – because, let’s be honest, everything is better as a cake 😉
Nanaimo Bar Cake
For my cake, I took all of the elements of the Nanaimo Bar and incorporated them into my layers. This towering cake has extra tall chocolate cake layers baked on a traditional Nanaimo Bar crust, filled with custard and topped with the fudgiest chocolate buttercream on the planet!
Nanaimo Bar Crust
The crust for the cake is the exact same crust you’ll see in my Nanaimo Bars. Once you add the crust to the cake pans, you’ll just set them aside until you’re ready to pour the cake batter onto the crust and bake them together.
Chocolate Cake
This chocolate cake is a new recipe and utterly delicious. It’s not as rich and dark as my Dark Chocolate Cake you’ll see in many of my chocolate cake recipes, but it still as a wonderful chocolate flavor. It’s also quite a bit taller than my Dark Chocolate Cake. This one should get between 1.5-2″ tall. The texture is moist and the slightest bit dense, in comparison to my Dark Chocolate Cake that is really tender.
Custard Filling
The custard filling is made with Bird’s Custard Powder. This is part of every traditional Canadian Nanaimo Bar recipe and is a total must for the cake. Just know that it’s not commonly found in the United States, so be prepared to order it on Amazon or head to your local World Market store.
Chocolate Fudge Buttercream
This Chocolate Fudge Buttercream is what dreams are made of! It’s incredibly rich and decadent and glides around the cake beautifully. Note that you’ll need a food processor or even a blender to make this buttercream. Making it in a mixer doesn’t blend all of the ingredients as well and you’ll notice it separates.
Ingredients Needed For A Nanaimo Bar Cake
- Graham crackers
- Unsweetened shredded coconut
- Almonds
- Cocoa powder
- Butter
- Eggs
- Bird’s Custard Powder
- Powdered sugar
- Heavy whipping cream
- Dark or semi-sweet chocolate chips
- Salt
- Buttermilk
- Granulater sugar
- Vinegar
- Baking soda
- Corn syrup
- Vanilla
Cake Making Tips
Don’t forget to follow my go-to tips for getting your cakes to rise and bake well:
- Preheat your oven for 30 minutes prior to baking.
- Use good quality pans like Fat Daddio.
- Spray your pans with nonstick spray and line with parchment paper.
- Don’t overmix your cake batter once you add the dry ingredients.
- Use room temperature wet ingredients.
- Use fresh baking powder.
- Bake until a toothpick inserted in the center of the cake comes out with a few moist crumbs on it.
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Video Tutorial
Nanaimo Bar Cake
Ingredients
FOR THE CRUST
- 1/2 cup (113 g) unsalted butter
- 5 tablespoons dark cocoa powder
- 1 teaspoon (6 g) salt
- 3 tablespoons (37.8 g) sugar
- 1 egg lightly beated
- 2 cups (220 g) finely ground graham crackers about 14 full crackers
- 1/2 cup (60 g) finely chopped almonds
- 1 cup (95 g) unsweetened shredded coconut
FOR THE CHOCOLATE CAKE
- 3/4 cup (169.5 g) unsalted butter at room temperature
- 1 3/4 cups (350 g) granulated sugar
- 5 large or extra large eggs at room temperature
- 3 1/4 cups (373.75 g) cake flour
- 3/4 cup (75 g) dark cocoa powder
- 1 1/2 tsp. (8 g) salt
- 2 cups (480 g) buttermilk at room temperature
- 1 1/2 tbsp. (21 g) white distilled vinegar
- 2 1/2 tsp. (10 g) baking soda
- ½ cup (120 g) sour cream at room temperature
- *This buttercream recipe makes enough to fill and cover your cake. If you want to add additional piping, you’ll want to make an extra ½ batch.
FOR THE CUSTARD FILLING
- 6 tablespoons (85 g) unsalted butter
- 5 tablespoons (72 g) heavy whipping cream
- 3 tablespoons (30 g) Bird's Custard Powder THIS brand
- 2 cups (250 g) powdered sugar measured then sifted
FOR THE CHOCOLATE FUDGE BUTTERCREAM
- 1 1/4 cups (283 g) unsalted butter
- 1 cup (125 g) powdered sugar measured then sifted
- 3/4 cup (75 g) dark cocoa powder
- 3/4 cup (276 g) light corn syrup
- 2 teaspoons (8.4 g) pure vanilla extract
- 10 ounces (283 g) dark or semi-sweet chocolate melted and cooled slightly
- 1/2 teaspoons (3 g) salt
Instructions
FOR THE CRUST
- Spray a three 8-inch round cake pans with nonstick spray, line the bottoms with parchment paper and spray again. Set aside.
- In a double boiler, over medium heat, melt the butter. Once the butter is melted, turn the heat off and whisk in the sugar, cocoa powder and salt until combined.
- While whisking vigorously, slowly pour in the beaten egg. Turn the heat back on to medium and cook until the mixture thickens slightly.
- Remove the mixture from the heat completely and add in the graham cracker crumbs, coconut, and almonds. Toss to combine evenly.Evenly divide the mixture between the three pans (about 6 ounces in each) and firmly press into place to create a crust.
FOR THE CHOCOLATE CAKE
- Preheat your oven to 325 degrees F.
- In a medium bowl, whisk together flour, salt and cocoa powder. Set aside.
- In the bowl of a stand mixer, fitted with the paddle attachment, combine the butter and sugar. Beat on medium speed until light and fluffy, about 2 minutes. Scrape down the sides of the bowl and mix again for another minute.
- Add the eggs, one at a time, being sure to mix and scrape down the sides of the bowl between each addition. Once all of the eggs are added, continue to beat on medium-high speed for about two mintues, until the mixture gets lighter in color and bigger in volume.
- With the mixer on low speed, add ⅓ of the flour mixture, followed by 1 cup of the buttermilk. Continue with another ⅓ of the flour, the second half of the buttermilk and then the remaining flour mixture. Stir until combined.
- In a small bowl, combine the vinegar and baking soda. The mixture will bubble. Add the mixture to the cake batter and stir on low until combined. Scrape down the sides of the bowl and mix again for another 20 seconds.
- Fold in the sour cream until no streaks remain.
- Divide the batter evenly between the prepared pans (20 ounces in each of the 8-inch pans). Bake for about 35-40 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs on it.
For the CUSTARD FILLING
- In a medium size mixing bowl, combine all of the ingredients and beat until smooth, about two minutes. The mixture should be fluffy and pale in color. If needed, add an additional tablespoon of heavy whipping cream to create a spreadable consistency.
FOR THE CHOCOLATE FUDGE BUTTERCREAM
- In a food process, combine the butter, powdered sugar, cocoa and salt. Mix until smooth, about 30 to 60 seconds, scraping down the sides and corner of the bowl about half way through.
- Add the corn syrup and vanilla, and mix until combined, about 30 seconds.
- Scrape down the sides of the bowl and add the melted chocolate. Pulse until the mixture is smooth and creamy, about 30 seconds.
FOR ASSEMBLY
- Place the first cake layer top side up, in the center of the cake board. Evenly spread half of the custard filling over the cake layer.
- Place the second cake layer on top of the custard filling and spread the remaining filling over the cake layer.
- Place the final cake layer, top side up, on the filling. Spread a thin layer of the chocolate fudge buttercream over the entire cake. Freeze the cake for 15 minutes. This is the crumb coat.
- Once the crumb coat is set, continue frosting the cake with the remaining buttercream.
Question – recipe says 1 1/4 c butter — but only 169 grams? My scale and Alexa says 1 1/4 c is 280 g. Which is it? I don’t want to mess this up at this point – too expensive and we’re too excited to eat it to just guess.
Yes it should be 283. I will fix that now.
Just wondering if you are using room temp butter for the custard filling and the frosting or leave it out for 30 min prior to using? Thank you. Made the cake already and going to finish it soon!
I’ve now made the bars and the cake. The bars are delicious but I definitely prefer this one in cake form! It’s absolutely perfect. Love the fluffy chocolate cake layers and the contrasting crunch from the crust on the bottom of each layer. I also think the custard tastes a tad too sweet in bar form, but it’s the perfect balance in the cake. This is definitely a winner (as all your cakes are). 10/10 would recommend.
Love all your cakes, Courtney! And I’ve never had any trouble with them… until this one. It turned out really tasty, even though I’m used to my Nanaimo bars with walnuts, but the fudge buttercream was kind of a pain. I don’t know what I did wrong! Made it in my food processor, some of the butter separated/melted, so I chilled it for a bit and then it was really stiff and sticky. I had to really work with it and I never got it quite smooth. So presentation was off for me, but it tasted great!
I would really like to make this and already have all the ingredients, but I’m wondering if the crust can be made without the almonds? What could I use as a substitute? I love almonds but my daughter is allergic to all nuts 🙁
Do a graham cracker crust.
This is the first recipe of yours that I have ever had a problem with. The icing was just such an weird consistency. Luckily I had made a 9×13 instead of layers as there’s no way the icing would have been proper for a layer cake.
This recipe looks incredible! I would love to make this using three 6″ pans. Would you happen to know how I could change the measurements to do so? Can’t wait to make this!
You could do half the recipe for a smaller version like that.
My nanaimo bar aficionados loved this cake. I’m glad I read the head note about using the food processor for the fudge buttercream. We felt like there should be more custard filling so I would probably double that next time.