200g70% dark chocolate chopped (good quality) DF as required
200gmilk chocolate chopped - DF as required
100gwhite chocolate chopped - DF as required
Base-line two 30 cm x 20 cm Swiss Roll tins with good quality baking paper.
Pre-heat the oven to 180 C/350 F/Gas 4.
In a small bowl, sieve the cocoa powder and add the melted butter, vanilla extract and boiling water. Mix together well and set aside.
Very carefully separate the eggs, making sure that NO yolk gets into the whites.
In a large bowl, weigh 100g of the caster sugar and add the egg yolks.
Whisk together until pale, thick and fluffy.
Add the chocolate mixture and whisk again to combine completely.
In a separate, very clean bowl (and using a clean beater), whisk the egg whites until they form stiff peaks.
Once stiff, add the remaining 50g caster sugar and whisk until you have a smooth meringue and the sugar has dissolved.
Beat one third of the egg white mixture into the chocolate mix to loosen.
Gently fold in the rest of the whisked egg whites, taking care to maintain as much air as possible in the mix.
Divide the mixture between the two tins and level out by gently tipping the tins to spread into the corners.
Bake for 12 to 18 minutes until the top just springs back to the touch.
Remove from the oven, but leave in the tins to cool completely. Cover the sponge tins with a clean, slightly damp tea towel while they cool.
Beat the softened butter in a large bowl until pale and smooth.
Gradually add the icing sugar and vanilla, continuing to beat until all the sugar is combined and you have a light, fluffy icing. If the icing feels too stiff to spread, add a tiny drop of milk to loosen.
To fill the sponges and roll
One at a time, turn the cakes out (upside-down) onto 2 large clean sheets of baking paper and very carefully peel off the original baking paper from the base of the sponges.
Carefully score a line along each short end, 2 to 4 cm in from the edge and turn the sponges so that one short end is nearest to you.
Mark a central line, half way along each of the sponges between the two original score lines.
Divide the buttercream in two and evenly spread one half completely over the top of each sponge, using a palette knife.
For the first sponge and starting from the front short edge, carefully roll up as tightly as you can, stopping at the half way point where you made the additional marker line.
Turn the whole sponge round and repeat the rolling process from the other short end until the two rolls meet in the middle and then cut down the centre of the sponge between the two rolls, to separate them.
Repeat the process with the other sponge, so that you have 4 long rolls.
Using a very sharp knife, very carefully trim a tiny slither off each end to tidy up the rolls.
Next, carefully cut each roll into thirds as evenly as possible, so that you have 12 mini rolls.
Place the rolls seam-side down on a cooling rack and chill in the fridge for about 15 minutes to firm up.
To coat in chocolate
Melt the plain and milk chocolate together in a medium glass bowl either set over a pan of lightly simmering water (stirring frequently) or in a microwave on medium setting at 30 second bursts, stirring well between each.
Place the cooling rack with the mini rolls over a baking tray (to catch the dripping chocolate) and spread or pour the chocolate over each mini roll to coat.
Leave aside until the chocolate has set.
Melt the white chocolate in a small glass bowl (as instructed previously).
Using either a small disposable piping bag with the tip snipped off or a spoon, drizzle the chocolate width-ways across the rolls to decorate. Leave to set.
* Note: nutritional information is an estimate & may vary according to portion size/ingredient variants.