Preheat the oven to 180C/350F/Gas 4.
Grease and line a 33 X 23 cm/13 X 9 in Swiss roll tin (jelly roll pan)
with baking parchment. Break the chocolate into squares and melt in a
bowl over a pan of barely simmering water. Remove from the heat and
leave to cool for 5 minutes. In a large bowl, whisk the sugar and egg
yolks until light and fluffy. stir in the melted chocolate. Whisk the
egg whites until stiff, but not dry, and then gently fold into the
Pour the chocolate mixture into the
prepared tin, spreading it level with a spatula. Bake for about 25
minutes until firm. Leave the cake in the tin and cover with a cooling
rack, making sure it doesn't touch the cake. Cover the rack with a damp
dish towel, then wrap in clear film (plastic wrap). Leave in a cool
place for at least 8 hours or overnight, if possible. Dust a large sheet
of baking parchment with icing sugar and turn out the roulade onto it.
Peel off the lining.
To make the filling, whip the double cream
with the coffee and liqueur until soft peaks form. Spread the cream over
the roulade. Starting from one of the short ends, carefully roll it up,
using the paper to help. Place the roulade, seam-side down, on to a
serving plate; dust generously with icing sugar and sprinkle with a
little grated chocolate before serving.
Cook's Tips: Make the roulade at
least 12 hours before serving, to allow it to soften. If liked, decorate
the roulade with swirls of whipped cream and chocolate coffee beans, or
with clusters of raspberries and mint leaves.