Preheat the oven to 180C. Grease a deep 22cm round cake pan. Line the base and sides with baking paper. Melt the chocolate seperately. Beat the eggs and sugar until well mixed. Strain egg mixture into a large bowl (to remove any “bits”) and continue to beat until thick and creamy. Beat in melted chocolate until combined. Then using a spatula, gently fold in cream and liqueur. Pour mixture into pan. Place pan in baking dish and pour enough boiling water into the baking dish to come halfway up side of pan. Bake 30 minutes, cover with foil and bake 30 minutes more. Discard the foil, remove the cake pan from the baking dish, cool cake in pan. Turn cake onto serving plate cover and refrigerate overnight.