Preheat your oven to 160°C fan and line a 13x9 inch Swiss roll tin with greaseproof baking paper.
Break up the dark chocolate into a microwave safe bowl and put it in the microwave on a high heat setting for 1 minute. Stir and return to the microwave for 30 seconds. Repeat this last step until the chocolate is smooth, being careful not to burn the chocolate.
Set aside the chocolate to cool.
Separate the eggs.
Whisk the egg yolks with the
caster sugar for 2 minutes, until light and creamy and pale in colour.
Fold in the cooled melted
chocolate until evenly distributed.
In a separate bowl, whisk the egg
whites until stiff peaks form.
Add a large spoonful of the egg
whites to the chocolate mixture to loosen it. Once mixed in, fold in the
remaining egg whites.
Pour the mixture into the
prepared tin, gently making sure it is level. You want to keep as much air in
the mixture as possible.
Bake in the oven for approx. 20
minutes, until the top is firm to the touch.
Allow the roulade to cool in the
tin.
In a food processor, blitz 6 of
the Oreos to a crumb consistency. If you don’t have a food processor, place the
Oreos in a food bag and break them up using a rolling pin.
Whip 250ml of the cream together
with the icing sugar, using an electric whisk/stand mixer, until it just holds
its shape.
Once whipped, add the crumbed
Oreos and fold in.
Carefully turn out the sponge
onto a clean sheet of baking paper, so the top of the sponge is on the bottom. Peel
away the used baking paper.
Spread the cream over the sponge,
leaving a 2cm gap around the edges.
Tightly roll the sponge from
short edge to short edge, using the baking paper to assist you. You can expect
cracks to form along the roulade.
Break up the milk chocolate into
a microwave safe bowl. Add the remaining cream and heat in a microwave on a high
heat setting for 40 seconds. Stir until smooth and if any lumps of chocolate
remain, put it back in the microwave for 20 seconds. Set aside to cool.
Drizzle the chocolate over the
roulade.
Roughly crumble the remaining 2
Oreos and scatter them across the top of the roulade to finish.
