Chocolate Swiss roll with mascarpone swirl

Start by making the Swiss roll. Preheat the oven to 170°C then line a 20 x 30cm baking tray with parchment

To a stand mixer fitted with the whisk attachment, add the egg whites and beat on a medium speed until you reach soft peaks. Gradually add 150g sugar, one tablespoon at a time, until thick and glossy. Continue to beat for a minute or so before setting aside

Sift together the flour, cocoa powder, baking powder and salt in a separate bowl

Next, in a third bowl, whisk together the egg yolks, vanilla and the remaining 150g sugar. Beat on a high speed until thick and pale 

Fold half of the egg white mixture into the egg yolk mix using a silicone spatula. Add the remaining egg white mix and continue to fold until combined

Next, sift in the dry ingredients, folding them through until combined

Drizzle over the butter and fold through again

Spread the batter evenly over the lined tray and use a palette knife to spread it out evenly

Bake in the oven for around 10 minutes or until just set

Remove from the oven and run a knife around the edge of the sponge to loosen it. Place a piece of baking paper over the sponge along with a chopping board then flip over so that the sponge comes out cleanly. Peel the baking paper away from the bottom of the sponge then roll it tightly starting with the narrow end. Allow to cool in the rolled shape

For the mascarpone cream, whisk together the double cream and sugar until soft peaks form, then add in the mascarpone and vanilla bean paste. Beat again until smooth then set aside 

Next, make the chocolate frosting. Beat together the unsalted butter with the cocoa powder until smooth, then mix in the icing sugar and vanilla. Once smooth, add in the milk. If still too stiff to spread, then add in a little more

To assemble the Swiss roll, first unroll the sponge cake. Spread over an even layer of the mascarpone cream, leaving about a 3 cm gap from one of the narrow ends of the cake

Begin rolling up the cake from the narrow end, making sure to go slowly and really roll the cake up tightly

Wrap the whole cake gently in cling film and chill in the fridge for an hour

Once the cake has chilled, remove it from the fridge and remove the cling film. Use an offset palette knife to spread the chocolate frosting over the Swiss roll evenly, then use a large palette knife to transfer the cake onto a serving plate

Garnish the Swiss roll with a dusting of icing sugar then slice and serve