Coffee & walnut Swiss Roll

Ah, the many joys of a Swiss Roll: one of those classic cakes that is just perfect sliced (thickly!) and served with a cup of tea or a mug of coffee.

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This is my Swiss Roll version of one of my favourite ever cakes: the ever-fabulous coffee and walnut cake.

I have added chocolate to the buttercream here, not just for a mocha vibe, but crucially the addition of melted chocolate to a buttercream such as this – which has liquid added (in the form of coffee here) – prevents the buttercream from splitting. That way you can add more of the liquid to get a well flavoured buttercream that is very stable. With other buttercreams, the liquid often takes the form of a fruit puree or alcohol.

I finished off this Swiss Roll with a few walnut halves dipped in chocolate, a drizzling of melted chocolate and a simple walnut crunch around the base of the Swiss Roll: the walnut crunch is simply the rest of the melted chocolate mixed with walnuts and left to set before being crushed up.

To prevent a Swiss Roll from cracking

To be honest, even if you were very brutal with this in terms of rolling it up, spreading over buttercream will hide any of the blemishes!

I make Swiss Rolls often with my students at school and in the cases where they go wrong or crack it is mainly down to:

• not weighing out the ingredients properly
• not whisking the eggs and sugar enough at the start
• beating in the flour rather than folding it in gently
• setting the oven temperature incorrectly

However, the following are also important:

• use plain flour and not self-raising: the whisked up egg gives the key raising agent here so if you use self-raising too, you end up getting a thicker sponge that can be harder to roll up.
• don’t over-bake the sponge: if you do, it will become too dry and will be more prone to cracking as you roll it up. I go just until it is nicely risen, slightly wrinkled around the edges and just starting to pull away from the sides.
• keep the sponge covered at all times while it cools: as soon as the sponge comes out of the oven I invert it onto a fresh sheet of greaserpoof, keeping the greasepoof it was baking in on still on it. This keeps the moisture from the steam trapped, helping the sponge keep pliable as it rolls but without it going at all soggy. Alternatively, placing a damp tea towel on top as soon as it comes out of the oven will achieve the same result.
• don’t dither when rolling it up: just go for it: spend a moment over the first part of the rolling up (the first few centimetres of the sponge), getting it quite tight at that stage, and then use the greaseproof paper to ease the rest of the sponge over itself to give a nice, well-rolled sponge.

Recipe: coffee & walnut Swiss Roll – serves 8-10

Sponge

• 3 large eggs, at room temperature
• 100g caster sugar
• 90g plain flour
• 1 rounded teaspoon cocoa powder
• 1 rounded teaspoon coffee powder or crushed granules

For the mocha butter cream

• 200g very soft unsalted butter
• 200g icing sugar
• 60ml strong espresso coffee, cooled
• 80g melted milk or dark chocolate, cooled

To finish

• a couple of tablespoons of caster sugar
• 100g walnuts, crushed
• zbout 50g melted chocolate to drizzle: milk, dark, white, ruby or a combination
• walnut halves

(1) Preheat the oven to 190C (fan) and line a large Swiss Roll tin with greaseproof.

(2) Using an electric hand whisk, whisk the eggs and sugar for about 10 minutes or until very thick and moussey: it should just start to hold its shape so when you lift the whisk out and let the mixture on the whisk fall back into the bowl, it very slowly disappears back into the mixure.

(3) Add the coffee powder and whisk for a further few minutes.

(4) Sieve the flour and cocoa powder over the bowl and fold in with a large metal spoon gently, until there is no flour visible. Spoon into the prepared tin and lightly flatten out.

(5) Bake for about 9-10 minutes or until risen and slightly coming away from the edges. Immediately invert onto a large sheet of greaseproof that has been sprinkled with caster sugar. Leave the greaseproof that was lining the cake tin on the sponge until fully cooled.
NB: this keeps the moisture in and will prevent the cake from cracking when you roll it up. You can also lay a damp tea towel on top.

(6) Make the buttercream by beating the ingredients together to give a very smooth mixture.

(7) Carefully remove the greaseproof off the sponge (the greaseproof that was in the cake tin) and arrange the sponge with one of the shortest edges facing you. Spread the buttercream thinly over the sponge, coming right to most of the edges, apart from the shortest edge that is nearest to you where you only spread to about 1cm from that edge ie) leaving a bit of sponge exposed.

(8) Sprinkle over the crushed walnuts and make a cut about 1cm away from the short edge nearest to you ie) up to where the buttercream was spread, going only about half-way into the sponge. This will help get a tight roll from the start:

(9) Roll up tightly, going away from you: it is easiest to give a tight roll at the edge that was cut and use the greaseproof the cake is on to help you roll it up. When you get the the opposite edge, lift onto a flat serving plate or platter.

(10) You can serve the Swiss Roll as it us, with a dusting of extra caster sugar or you can spread over any extra buttercream and decorate with melted chocolate drizzled over and walnut halves.