Step 1

Heat oven to 220C/200C fan /gas Line a 23 x 33cm Swiss roll tin with baking parchment and oil lightly. Whisk the caster sugar and yolks in a bowl until pale and thick. Melt the chocolate with 4 tbsp cold water in a bowl set over a pan of simmering water. Stir in the sugar mix.

Step 2

Whisk egg whites to stiff peaks. Stir a spoonful into the chocolate, then fold in remaining using a large metal spoon. Pour batter into tin and bake for 12-14 mins until risen and just firm. Leave in tin until cold.

Step 3

Lay a sheet of baking parchment on a board. With one bold movement, turn the cake onto the paper, then lift off the tin. Carefully peel away the lining paper.

Step 4

Spread the whipped cream all over the cake, then scatter over the berries with a dribble of Drambuie, if you like. Starting at the long side opposite you, use the paper to roll the cake towards you. Transfer to a serving dish.

Step 5

For the buttercream, beat the butter, then sift in sugar and cocoa. Add milk and mix together. Spread over cake, use a fork to create a log effect, and chill until needed. Decorate, dust with icing sugar and serve.