For the tiramisu, place the egg yolks and icing sugar into a large bowl and whisk with an electric hand whisk until pale and frothy.
Add the softly whipped cream and mascarpone and a dash of the coffee liqueur, and stir well.
In a separate bowl, whisk the egg whites until stiff peaks form when the whisk is removed. Fold into the cream mixture.
Mix the rest of the coffee liqueur with the chilled coffee in a shallow dish.
Dip half of the sponge fingers into the coffee mixture. Place in the base of a large dessert glass, then spoon over half of the cream mixture. Dip the rest of the sponge fingers into the coffee mixture, then place on top of the cream mixture in the glass. Finish with the remaining cream mixture.
Dust with cocoa powder and grated white chocolate and chill for 30 minutes, if time permits.
For the almond brittle, place the caster sugar into a frying pan and melt over a gentle heat until it turns a caramel colour.
Add the almonds and stir to coat. Pour onto a baking sheet lined with baking paper and leave to cool.
When cold, break the brittle into pieces and use to decorate the top of the tiramisu. Serve.
