Coffee Walnut & Kahlua Cake

Coffee Walnut Birthday Cake with Kahlua Buttercream

A few months late… but I’m finally posting this birthday cake that I made back in July! It was 4 layers of deliciousness! When you’ve got nuts and oil in the batter, you know it’s going to be a super moist cake. Paired with silky smooth, not overly sweet buttercream…it was just heavenly! I’d made Kahlua coffee French buttercream before, using egg yolks, but opted this time for a Swiss meringue buttercream, using egg whites (both are equally yummy!).

If you’re a coffee/Kahlua lover, you’ve got to give this cake a try! And if you’re looking for the same flavours but with a bit of crunch, make sure to check out Sans Rival with Kahlua Coffee buttercream.

Coffee Walnut Birthday Cake with Kahlua Buttercream

Did you make this recipe?

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Coffee Walnut Cake with Kahlua Buttercream

(Cake recipe adapted from Epicurious)


Coffee Walnut Cake


170g unsalted butter, plus more for greasing pans
100g (about 1 cup) walnut meal
1/2 cup plus 2 tablespoons vegetable/extra light olive oil (I used melted refined coconut oil)
250g (2 cups) all-purpose flour
2-1/4 teaspoons baking powder
1/2 teaspoon salt
1/2 teaspoon baking soda
4 large eggs
200g (1 cup) sugar 
2 teaspoons vanilla extract
1 tablespoon instant espresso powder
2 tablespoons whole milk


1. Position rack in the middle of the oven, preheat to 325F. Lightly butter 2 – 8″ diameter cake pans and line the bottoms with 8″ parchment paper rounds.

2. Place walnut meal in a medium frying pan over medium heat. Stir to make sure it toasts evenly and does not burn.  You just want to lightly toast it, so it should only take a few minutes.  Once done, immediately transfer to a shallow bowl to cool.

3. Place 170g unsalted butter in a small saucepan and cook over medium heat, stirring often, until foamy and browned (takes about 6-8 minutes). Remove from heat and immediately stir in the oil. Set aside.

4. In a large bowl, combine walnut meal, flour, baking powder, salt and baking soda.

5. In the bowl of a stand mixer, beat together 4 large eggs, sugar, vanilla extract and espresso powder until thickened.

6. Stir whole milk into the brown butter mixture. With the stand mixer running on low speed, gradually pour the brown butter mixture into the egg mixture. Beat until combined.

7. Add in dry ingredients and beat until well mixed and smooth. Divide batter evenly between the 2 pans.

8. Bake 20-22 minutes, or until skewer inserted into the centres comes out clean. Rotate the pans halfway through if necessary, for an even bake.

9. Turn out cakes onto racks, remove parchment papers and allow to cool, while you prepare the buttercream. (Recommended: Once the cakes have cooled down, wrap them in plastic wrap and refrigerate for at least a couple of hours. A chilled cake is less crumbly and easier to slice). 

Kahlua Swiss Meringue Buttercream


8 large egg whites
250g (1-1/4 cups) sugar
1/4 teaspoon cream of tartar
1 teaspoon vanilla extract
680g unsalted butter, room temperature, cut into small pieces
5 tablespoons instant espresso powder
6 tablespoons Kahlua


1. Combine egg whites, sugar and cream of tartar in a heat-proof bowl. Set bowl over a medium saucepan filled with simmering water (you only need about 2″ of water; make sure bowl does not touch the water). Stir constantly with a rubber spatula, making sure to scrape down the sides too, until sugar has dissolved. It will take about 10-15 minutes (an easy way to check doneness is to rub a bit of the mixture between your thumb and forefinger. It should not feel grainy).

2. Pour egg white mixture into the bowl of a stand mixer fitted with a whisk attachment. Beat starting at low speed and gradually increasing to high.

3. Add in vanilla, and continue to whisk until meringue is is shiny and forms stiff peaks (8-10 minutes).

4. Replace the whisk with a paddle attachment, and with the mixer running on low speed, gradually add in the softened pieces of butter, one at a time. Make sure each piece is well incorporated before adding more.

5. Once all the butter has been added, increase speed to high and beat for a few minutes until you get a nice, smooth buttercream consistency. (Do not worry if the mixture looks curdled; just keep beating and it will eventually come together!).

6. Stir espresso powder into the Kahlua.  Once dissolved, add this mixture into the buttercream. Beat on medium low speed for about 5 minutes, until fully combined, scraping down the sides as needed.

7. Chill buttercream in refrigerator while you make the syrup and prepare to assemble the cake.

Syrup for the cake


50g (1/4 cup) sugar
1/4 cup water
1/2 teaspoon instant espresso powder
1 tablespoon Kahlua


1. Heat sugar and water in a small saucepan. When the sugar has dissolved, remove from heat. Stir in Kahlua and espresso powder.


1. Remove cakes from the refrigerator. Use a serrated knife to level the surfaces.  Then slice both cakes horizontally in half, to get 4 cake layers. (You’ll want to set aside one of the bottom layers to be used as the cake’s top layer).

2. Place 1 cake layer on a cake board or plate. Brush syrup over the surface.

3. Use an offset spatula to spread on the buttercream.

4. Repeat steps 2 & 3 for the remaining layers. For the top layer, make sure you place it cut side down, to ensure a smooth, crumb-free surface for decorating.

5. Once all the layers are assembled, decorate the cake as desired.  Chill cake until ready to eat.

Note: Leftover cake can keep in the fridge, in an airtight container for about 5 days. If you have any leftover buttercream, it can also be refrigerated for about a week in an airtight container, or up to 3 months in the freezer.  Just leave out on the counter at room temperature to thaw, and then give it a good stir or re-whip it before using.


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