Coffee & Walnut Cake with French Coffee Buttercream

10-12 SLICES

Coffee and walnuts are a classic combo. I have created this version that has a slightly more dense and nutty crumb then the original. The layers are brushed with a coffee syrup and filled with the a luxurious French buttercream, laced with plenty of coffee flavour. It can be made in both gluten and gluten free versions. Just see all my notes for how. Check out all my tips below, before you make it.

TIPS: You can use either espresso shots or instant coffee granules dissolved in a tiny amount of boiling water in this cake, just not Americano coffee as it won’t be potent enough. You need a candy thermometer to make the buttercream. Buy one online. I personally think every home kitchen should have one. It’ll open up the doors to the sweet recipes you will be able to cook and make like easier for cooking methods such as deep-frying.

Use regular salted butter for bother the cake and buttercream. You could choose unsalted butter if you like, but I personally like the saltiness in this. Make sure you seek out dark brown sugar.

Having butter at room temp just makes whisking a lot easier as the butter is softer. If I am disorganised and take the butter straight from the fridge, I just zap it in the microwave for 10-20 seconds before proceeding with the recipe.

The buttercream is best made when you are ready to ice and used immediately. If it is allowed to harden it is tricky to whisk it back to a good smooth consistency.

IMPORTANT NOTES: As the buttercream contains raw egg yolks that are only cooked through hot sugar syrup being added to them, I am sure to use very clean pasteurised eggs and serve it within a day or two of making. Leftovers can be frozen. It is very important to store this cake in the fridge. You can serve it at a cold temp or bring it to room temp for half an hour or so before serving.

Ingredients

Cake

250g butter, at room temp

250 dark brown sugar

3 eggs

1 tsp vanilla

100g ground almonds

100g walnuts, ground to a fine powder

2/3 cup plain flour (if making gluten free, use 3/4 cup gluten free flour)

1 tsp baking powder (gluten free, if needed)

1 strong 30ml shot espresso coffee or 1 tsp coffee dissolved in 2 tsp boiling water

French Coffee Buttercream

2/3 cup sugar

1/4 cup water

5 egg yolks

250g butter, at room temp

1 strong 30ml shot espresso coffee or 1 tsp coffee dissolved in 2 tsp boiling water

1 tsp coffee extract

Coffee Syrup 

1/4 cup sugar

1/4 cup water

1/2 tsp instant coffee powder or 1/2 espresso shot

To Assemble

60g whole walnuts

Method

Cake

Make the cake in the usual cake-making way. Cream the butter and dark brown sugar until creamy and pale. Add in the eggs and vanilla and whisk until just combined. Stir in the ground nuts. Finally, tip in the flour, baking powder and cooled espresso or dissolved coffee and stir through until the mixture is thoroughly combined.

Pour in a baking paper lined 20-22cm round tin. Bake a 160 degrees Celsius, conventional for 45 mins to an hour until a skewer comes out clean.

Allow the cake to cool a little, remove from the tin and refrigerate until cold.

French Coffee Buttercream

When the cake is ready to ice, make the buttercream. Place the egg yolks in an electric stand mixer and beat until pale and frothy. It takes a few minutes.

Meanwhile place the sugar and water in a small sauce pan and bring to the boil. Clip in a candy thermometer. Allow the syrup to boil until it reaches 114 degrees Celsius. Immediately remove form the heat and while the mixer is slowly running, carefully but swiftly pour the syrup in a steady stream into the egg yolks. Don’t worry if there is a tiny bit of sugar syrup left in the saucepan. The recipe accounts for this. If you feel the outside of the bowl, it will be very hot. Continue whisking at high speed until the egg yolk and sugar mixture is cooled down to room temp. If you feel the outside of the bowl, it should be coolish to touch.

Add spoonfuls of the butter, continuing to whisk, until it is all added in and just smooth. Pour in the cooked espresso or dissolved coffee, a teaspoon at a time, whisking briefly between additions. Whisk only until just combined and smooth. Use immediately.

Coffee Syrup 

Place the sugar, water and coffee into a small saucepan. Bring to the boil. Take off the heat and allow it to cool completely.

To Assemble

Split the cake in half to create two layers. Brush the top of each layer with a little of the coffee syrup. On the base layer, spread half of the French coffee buttercream. Place the second cake layer on top. Spread with the remaining buttercream. Sprinkle with walnuts. Serve in wedges with a hot cup of coffee to accompany it.