This Coffee & Walnut Traybake Cake is such an easy and delicious cake for coffee lovers! As it's made in a sheet cake style, it's so simple to decorate and serve to your guests. This makes it a great cake for parties, bake sale and any celebration. The fluffy coffee sponge is filled with tasty walnut, on top is a silky smooth coffee buttercream, and it's decorated simply with more walnuts.

Ingredient Tips & Equipment Information

Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
I used a baking spread for the cake and unsalted butter for the buttercream.
I used golden caster sugar for the cake, but regular caster sugar will work if you prefer.
If you want to make this into a coffee traybake cake, you can leave out the walnuts.
I used Nescafe Azera instant coffee for this recipe, you will need an instant coffee to make this cake. You can also boost the flavour with coffee extract* if you like, I like Nielsen Massey's*.
You will need a 12" x 9" traybake tin for this recipe. However, if you want to make it in a 9" square tin, check the recipe notes for the ingredient details.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales*. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons* and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.

For the full recipe with measurements, head to the recipe card at the end of this post.

How to make Coffee & Walnut Traybake Cake

Start by dissolving the instant coffee into boiling water, set it aside to cool. In a large mixing bowl, mix together the baking spread and golden caster sugar for 3 minutes. Add the eggs, coffee and water mixture and, if using, the coffee extract. Mix them in well.

Add the self raising flour and mix it in gently. Fold in the chopped walnuts. Spread the mixture out into the tin.

Bake the cake for 25-30 minutes or until a thin skewer inserted in the centre comes out clean. Leave to cool fully. To make the buttercream, first mix the coffee with boiling water and leave to cool. Mix the butter for a couple of minutes until smooth and creamy, then add the icing sugar, coffee and water mixture (and coffee extract if using) and mix until smooth. Spread or pipe it onto the cake and decorate with whole and chopped walnuts.

For the full recipe with measurements, head to the recipe card at the end of this post.

How long does the cake last for and can you freeze it?

The cake will last for 3-4 days in an airtight container in a cool place. You can freeze both the cake and the buttercream. To freeze them separately, wrap the cake well in cling film or put it in an airtight container. The buttercream can be frozen in a sealed tub. To freeze the cake decorated, freeze on a plate until frozen solid, then carefully wrap in cling film. Remove the clingfilm when you take the cake out of the freezer to defrost, as if it defrosts with it still on it could damage the appearance of the buttercream.

Can you make this cake with plain/all purpose flour?

Self raising flour, which is very commonly used in the UK where I am based, already contains a raising agent and a little salt too. Therefore if you want to swap it for plain or all purpose flour, you will need to add some additional baking powder and also a little salt if you like. Some people like to add salt to cake recipes and some don't, so I'll leave that up to you as it won't affect the bake. The general advice is to add 2 teaspoons baking powder (a measuring teaspoon, not the kind you stir your coffee with) per every 200g plain or all purpose flour. So for this recipe you'd need to add an additional 2 teaspoons baking powder. Please note, I have not tested this recipe using plain or all purpose flour.

What size tin do you need for this cake?

This recipe is best made in a 12" x 9" (36.5cm x 26cm) traybake tin with deep sides (4cm or 1.5"). However, if you'd prefer to make it in a smaller 9" square tin, check the recipe card notes section for details on the measurements.

Can this recipe be made into a larger cake or cupcakes?

Yes - check out my Coffee & Walnut Cake or Coffee & Walnut Cupcakes recipes for details.

Do you need an electric mixer to make this recipe?

While you can absolutely make this recipe with a wooden spoon and some elbow grease, I do recommend using an electric mixer for the best results. The cake will be lighter and fluffier when made with an electric mixer. The buttercream will also be smoother. You don't have to use an expensive stand mixer either, you can get electric hand whisks for as little as £10!

How many people does this cake serve?

It completely depends how you slice it up, which is great because it makes this such a versatile cake for parties and gatherings. I love a big chunk of cake so I cut it into 12 slices, but for a party you may prefer to cut it into smaller slices so it feeds more people. You can cut into 16 slices, or even 24 slices.

Can this cake be made gluten free?

Yes! For gluten free you can replace the self raising flour with a gluten free self raising flour blend. If you only have a gluten free plain flour blend, you will need to add additional baking powder. The general advice is to add 2 tsp baking powder per 200g flour, so for this recipe you'd need to add 2 teaspoons baking powder. You may also like to add ½ tsp xanthan gum for better texture. Please do check the labels for everything you use to make the cake if you are serving it to someone with an allergy or intolerance.

Can this cake be made dairy free?

For a dairy free version, use a dairy free baking spread for the cake. For the buttercream you will need a dairy free butter alternative. I recommend Flora Plant or the Stork Baking Block for the buttercream, as they give the best texture. And also dairy free milk. Please do check the labels for everything you use to make the cake if you are serving it to someone with an allergy or intolerance.

More tips for making the Coffee & Walnut Traybake Cake:

I spread the buttercream onto the cake, but you could pipe it on if you prefer.
You can decorate this cake with anything you like!

Troubleshooting

If you have any questions about this recipe, or if something went wrong and you need help, please use the comment form below and I will get back to you. You can also get in touch with me on my Twitter, Instagram or Facebook. I'd love to hear from you!

Recommended equipment & ingredients*

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