2. Butter four ramekins (about 7.5cm in diameter), then dust liberally with cocoa, shaking out any excess.
3. Slowly melt the chocolate and butter in a small bowl set over a pan of hot water, then take off the heat and stir until smooth. Leave to cool for 10 minutes.
4. Using an electric whisk, whisk the whole egg, egg yolk and sugar together until pale and thick, then incorporate the chocolate mixture. Fold in the liqueur, followed by the flour. Divide the chocolate mixture between the ramekins and bake for 12 minutes.
5. Turn the chocolate fondants out on to warmed plates. Dust the tops with icing sugar and serve with a dollop of creme fraiche or a scoop of vanilla ice cream.