- 1 tsp oil, for greasing
- 170g Belgian dark chocolate, broken up
- 5 medium British free-range eggs, separated
- 225g golden caster sugar
- 200ml British double cream
- 1 tsp vanilla extract
- 1 tbsp icing sugar, sifted
- 80g smooth white chocolate, broken up
- Preheat the oven to 200°C, fan 180°C, gas 6. Grease a 33cm x 23cm swiss roll tin and line with baking parchment.
- Melt the dark chocolate in a bowl over a pan of just simmering water, making sure the bowl doesn’t touch the water. Stir until smooth, then set aside.
- In a large, clean bowl, whisk together the egg yolks and all but 1 tablespoon of the caster sugar until pale and thick. Mix in the melted chocolate and 1 tablespoon hot water until smooth.
- In another clean bowl, whisk the egg whites until stiff, then whisk in the remaining 1 tablespoon caster sugar. Lightly fold into the chocolate mixture using a large metal spoon, then spoon into the prepared tin. Bake for 15-20 minutes, until risen and springy to the touch.
- Cover with a sheet of baking paper and a damp tea towel. Leave for 15 minutes. Remove the tea towel and leave to stand until completely cold.
- In a bowl, whip the cream, vanilla extract, and icing sugar until soft peaks form. Removed the paper and turn out the roulade onto a clean sheet of parchment. Spread with the cream to within 2cm of the edge. With the long side towards you and, using the paper to help, roll up the roulade.
- Melt the white chocolate as in step 2. Using a teaspoon, drizzle the melted chocolate all over the roulade. Cut into slices to serve.