Beat the egg and egg yolk over a bain-marie at about 80ºC until frothy. Then beat over iced water until cold. Add the liqueur and amaretto biscuits and fold in the whipped cream. Pour the mixture into moulds and leave in the freezer for at least 3 hours covered with cling film.
Toast the walnuts in a frying pan. Set the nuts aside and heat the remaining ingredients in the pan whilst stirring until the sugar has dissolved. Mix in the nuts and put the mixture onto a sheet of baking paper, spread it out and leave to cool. Afterwards cut into small pieces with a knife.
Dip the parfait in its mould in lukewarm water and then tip onto a plate. Sprinkle the brittle over the top and garnish with the quartered figs and fresh mint.