Oil and line a 1-litre loaf tin with cling film. Put the coffee, Kahlúa, egg yolks and sugar in a bowl. Put the egg whites in a large bowl and pour the cream in another.
Beat the egg whites until stiff with an electric whisk, then quickly beat the cream until it holds its shape. Now beat the egg yolk mixture until thick and leaving a trail (if you beat everything in this order, you don’t have to wash the whisks in between).
Fold the cream into the coffee mixture then carefully fold into the whites. Fold through the Toblerone and tip into the loaf tin. Cover the surface with cling film. When frozen, wrap in foil and freeze. Will keep for up to 6 weeks. To serve, unwrap and turn onto a platter. Strip off the cling film and serve topped with the chocolate curls and a sprinkle of cocoa powder.
For the biscotti: preheat the oven to 190C. Pour the self-raising flour into a bowl and stir in the golden caster sugar, espresso powder and almonds.
Beat together the eggs and butter. Add to the bowl and mix to a dough. Turn out onto the surface and cut in half. Shape each half into a log. Place on a tray lined with baking paper and flatten each until about 7cm wide. Bake for 20 minutes. Leave to cool for 20 minutes.
Using a serrated knife cut each log into about 24 slices. Space the biscuits slightly apart and return to the oven for a further 15 minutes. Cool and serve.