Whip the egg yolks and the sugar until the latter melts. Add the sifted flour. Combine without letting go lumpy. Boil the milk, pour slowly onto the mixture, beating continuously. Bring to a boil, stirring with a wooden spoon to prevent from sticking to the bottom. After boiling for a minute, remove from the heat, little by little add the cocoa, always stirring. Allow to cool down completely, then add the whipped cream little by little. Sprinkle with a little Grand-Marnier, stir well until perfectly smooth. Serve chilled.
