Chocolate dream dessert

Line the bottom of a 28 x 11 x 7 cm dish with butter paper and spray well with non-stick spray.
Melt the chocolate in the microwave oven on 70 per cent power or over boiling water. Stir occasionally. Add the liqueur, mix well and cool.
Cream the butter and castor sugar together, add the egg yolks and beat well. Add the cooled chocolate and mix. Whisk the egg whites till soft peaks have formed and fold into the mixture. Fold the crushed biscuits into the mixture. Turn the mixture into the prepared dish and spread evenly. Cover with plastic wrap and chill for at least 4 hours, preferably overnight.
Turn out onto a serving platter and slice. Halve the slices if desired and serve on a side plate.
Serves 4-6.