Preheat the oven to 180C/350F/Gas 4.
Spread the almonds on a baking tray and bake for 7-10 minutes, or until they turn golden-brown. Grind them coarsely in a food processor, being careful to stop when they resemble grains of rice.
Cream together the butter and sugar in a bowl until light and fluffy.
Sieve the cocoa and add it to the butter and sugar. Beat hard to incorporate.
Lightly beat together the whole egg and the egg yolk and then add the eggs to the mixture. Stir well until everything is well blended together.
Crush the biscuits with a rolling pin, add to the mixture together with the ground almonds and the orange-flavoured liqueur. Mix thoroughly.
Line a 20x10cm/8inx4in loaf tin with cling film and spoon the mixture into it pressing down all the time to eliminate any air bubbles and, when it is all in, bang the tin hard on the work surface. Cover with cling film and chill for at least four hours.
Get an oval dish, turn the tin upside down over it and peel off the cling film.
Decorate with candied flowers or sugared almonds or whipped cream before serving.