Nanaimo Bar Birthday Cake


Oh the Nanaimo bar birthday cake. I would consider this to be the cake I should be proudest of, and therefore chose it as the subject of my first post on Chateau Gateau! 


The initial concept of a Nanaimo bar + cake mash-up was (unfortunately) not my idea. When my buddy Nate’s birthday was around the corner,  I asked him what kind of birthday cake he wanted, because that’s just how you roll when you bake excessively. A few ideas were tossed around until the light bulb turned on, and Nate came up with Nanaimo bars. As wonderful as they are, Nanaimo bars are not cake; hardly fitting for a birthday. This is where Nate had the brilliant idea to ask if I could make a cake version out of our great Canadian treat, so I said “For sure! I’ll Google around and find a recipe!” This was not the case. My searching revealed no cake-ified Nanaimo bar recipes, with the exception of a cupcake version from BS’ in the Kitchen. Unacceptable! Nate must have a proper cake for his birthday! This is when I made my decision to create a cake of my own design to fit all of the Nanaimo-y, cake-y criteria. And then it was born, the first (that I know of) Nanaimo cake!



I must confess that all I did was take the Choco Choco Birthday Cake recipe from Sweetapolita (aka my #1 baking idol) and use the custard filling from Nanaimo bars between layers. Somehow I’m still proud of myself. I also have to admit that there were some road bumps pre-cake assembly. Initially I found the consistency of the icing I made to lack fluffiness and was streaky, so I decided to put it in the fridge while I made the custard filling. Bad idea. When I whipped it back up to revive the texture, it became all curdle-y. Pretty gross looking to be honest. It isn’t a buttercream icing, so I wasn’t really sure what to do. I tried adding icing sugar and I tried whipping it for a few minutes on a high speed. It was fine at first, but the longer it sat the more it re-curdled. Needless to say I was stressing, because of course I was supposed to drop the cake off that evening. More frantic Googling resulted in a ‘how to save your icing’ sort of page that suggested everything I had already tried except for adding chocolate (not really a helpful tip when you’re already making chocolate icing), and bringing the icing to room temperature. One warm water bath and a few more minutes of whipping later my icing was fixed!

Looking back my icing fiasco I really should have known better. Baking is basically chemistry that you eat, and I may or may not have a minor in chemistry… Oops? Cooling the icing disrupted the emulsion, causing the butter to separate out of the milk. I feel silly. I also didn’t smooth out the bubbles in the icing after all the fixing because I was scared it would get curdle-y again, which is why the cake looks a little sketchy.

Either way, ‘Nanaimo cake: Round II’ went much more smoothly!


I was pretty excited

Today I was feeling kind of tired and lazy after work so I halfed the recipe. I used two 4-inch springform pans, because I find the smallness cute, and used the rest of the batter to make mini cupcakes (little seemed to be the trend).


I find preparing all of the ingredients before hand it especially helpful in recipes like this one, where you’re heating over the stove. Mise en place is a thing for a reason, and probably why round two worked so much better than round one.


Nanaimo Bar Birthday Cake

(Adapted from Sweetapolita and the City of Nanaimo’s Nanaimo bar recipe)


For the cake:

  • 5 oz (145 g) semisweet or bittersweet chocolate, chopped
  • 2 ¼ sticks (9 oz or 260 g) unsalted butter, room temperature
  • 2 ¾ cups (11 oz or 315 g) cake flour, sifted
  • ¼ cup (24 g) unsweetened cocoa powder (if it’s Dutch-process add ¼ tsp of cream of tartar or lemon juice)
  • 2 tsp baking soda
  • 1 tsp baking powder
  • ½ tsp salt
  • 4 eggs, room temperature (30 minutes at least)
  • 1 cup (7 oz or 200 g) granulated sugar
  • 1 cup (7.5 oz or 220 g) packed light brown sugar
  • 1 ½ tsp pure vanilla extract
  • 2 cups sour cream

For the filling:

  • ¾ cup (170.5 g) unsalted butter 
  • ¼ cup (60 ml) cream
  • 3 cups (375 g) icing sugar
  • ~½ cup each of finely chopped almonds and coconut (optional, but more true to Nanaimo bars)

For the frosting*:

  • 1 cup (7 oz or 200 g) granulated sugar
  • 6 tbsp (47 g) all-purpose flour
  • 6 tbsp (36 g) unsweetened cocoa powder (if it’s Dutch-process add ¼ tsp cream of tartar or lemon juice)
  • 1 ½ cups (360 ml) whole milk
  • 4 oz (115 g) semisweet or bittersweet chocolate, finely chopped
  • 1 tbsp pure vanilla extract
  • 6 sticks (3 cups or 680 g) unsalted butter, room temperature


For the cake:

1. Preheat oven to 350°F and put oven rack in the middle. Grease two 8-inch round cake pans and dust with cocoa powder (flour is okay too). Tap out excess and set aside.

2. Melt the chocolate and butter until smooth. You can do this in the microwave in 20 second intervals, or in a heatproof bowl over a pot of simmering (not boiling) water (be sure the water does not touch the bottom of the bowl). Let cool.

3. In a medium bowl, sift together flour, cocoa powder, baking soda, baking powder and salt.

4. In the bowl of an electric mixer fitted with the paddle attachment, beat the eggs, sugar and vanilla on medium speed (#4 on KitchenAid) until light and fluffy, about 4-5 minutes.

5. At low speed (#2 on KitchenAid), mix in melted chocolate until incorporated, followed by dry ingredients in 3 batches alternately with sour cream, beginning and ending with dry ingredients and mixing until each addition is just incorporated. Do not over-mix.

6. Spread batter evenly in pans (you can weigh batter in pans for perfectly even layers) using a small offset spatula. Rap pans several times on counter to eliminate any air bubble and bake on the centre rack until a toothpick comes clean and remove cakes from oven, about 35-40 minutes. Be sure to not open oven before 20 minutes (with these cakes, ideally 30 minutes) to check cakes and take care to not over-bake.

7. Let cakes cool in pans on wire racks for about 10 minutes, and then carefully loosen them from the edges of the cake pans with your small palette knife and gently invert cakes onto racks to cool completely (about an hour).

For the filling:

1. Cream the butter, cream, custard powder, and icing sugar together well. Beat until light

2. Mix in the coconut and almonds (optional)

For the icing:

1. Whisk together sugar, flour, cocoa powder and a pinch of salt in a  small heavy saucepan over medium heat, then add milk and cook, whisking  constantly, until mixture boils and is smooth and thick** (5-8 minutes).

2. Remove saucepan from heat and whisk in chocolate and vanilla, until smooth. Transfer mixture to a heatproof bowl to cool to room temperature, covering surface with parchment paper to prevent a skin from forming.

3. In electric mixer fitted with the paddle attachment, beat butter until creamy, about 5 minutes, then gradually add cooled chocolate mixture, beating until frosting is fluffy and spreadable.

Cake assembly:

1. Cut each cake in half horizontally using a long serrated knife or cake leveler

2. Put 1 layer on a cake stand or large plate (cut side up) and spread top with 1 /3 of the custard filling. If the almond and coconut are not mixed in the filling, sprinkle 1/3 of each on top of the filling and lightly press in before stacking the next layer of cake. Repeat with the other cake layers

3. Spread the top and side of cake with a thin layer of frosting***. If frosting is too soft, put it in the refrigerator for a few moments****, remove and carry on. Chill the cake for 20 minutes.

4. Ice the cake as you please and enjoy 🙂

* I found that these portions yielded 3 or more extra cups of icing (the original recipe does not have a filling)

** Don’t leave the stove! Once it starts to thicken, it does so very quickly.

*** I like doing a crumb coat, though it wasn’t actually mentioned in the original recipe

**** I’m very untrusting of this advice…

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