This impressive white chocolate dessert from Great British Bake Off star Mary Berry is perfect for dinner parties, especially as you can make it the day before.
- 6 eggs, separated
- 215g / 7½oz caster sugar
- 120g / 4oz self-raising flour
- 45g / 1½oz cocoa powder, plus extra for sifting
- White and dark chocolate curls, to decorate
- For the white chocolate butter cream
- 3tbsp milk
- 60g / 2oz white chocolate, chopped
- 4tbsp coffee liqueur
- 120g / 4oz icing sugar, sifted
- 175g / 6oz butter, softened
Grease two 33 x 23cm (13 x 19-inch) Swiss roll tins then line the tins with non-stick baking parchment.
In a large bowl, with an electric mixer on full speed, beat the egg whites until soft peaks form. Gradually sprinkle in 75g/2½oz sugar, beating completely until the sugar completely dissolves and the whites stand in stiff peaks.
Preheat the oven to 190°C (375°F/gas mark 5). In another large bowl, using an electric mixer, beat the egg yolks and remaining sugar until very thick and lemon-coloured. Add the flour and 45g/1½oz cocoa. Beat until well mixed, occasionally scraping the bowl with a rubber spatula. With a rubber spatula or wire whisk, gently fold the beaten egg whites into the egg yolk and sugar mixture, one third at a time.
Spoon the mixture into tins, spreading evenly. Bake for 8-10 mins or until the tops of the cakes spring back when lightly touched with your finger.
Sift the cocoa over 2 clean tea towels. When the cakes are done, immediately turn the cakes out onto the towels.
Carefully peel the baking parchment off the cakes. If you like, cut off the crisp edges. Starting at a narrow end of each cake, roll cakes with towels, Swiss roll-style. Place the cake rolls, seam-side down, on wire racks and leave to cool completely.
Meanwhile, prepare the white chocolate butter cream. In a small, heavy saucepan, heat 3tbsp of milk over a medium heat until tiny bubbles form around the edge of the pan. Remove the saucepan from the heat.
Using a wire whisk, beat in the chopped white chocolate. Mix until the chocolate melts then stir in the coffee liqueur. Cool, then refrigerate until cold for about 30 mins, stirring occasionally.
Place the icing sugar and softened butter in a large bowl. (Don’t use margarine as the butter cream will separate). Using an electric mixer, beat for 10 mins or until light and fluffy, scraping the bowl often with a rubber spatula.
Gradually beat the white chocolate mixture into the butter cream until smooth, occasionally scraping the bowl with the spatula.
Now, unroll 1 cooled cake and use a palette knife to spread with about one third of the butter cream. Starting at the same narrow end, roll the cake without the towel. Unroll the second cake and spread with another third of the butter cream. Next, join the cakes – along the narrow end of the second cake, place a narrow end of filled cake roll. Finally, roll the cakes together by rolling the second cake around the first cake roll.
When cutting roulade, it's important to slice it cleanly so that the filling is seen at its best. For perfect results, dip a long serrated knife in hot water before slicing. Wipe the blade with kitchen paper after cutting each slice and dip again in water.