Heat the milk, put in the ground coffee to infuse, cover. Leave to cool. Break the chocolate in a mixing bowl, melt in a double boiler, over the heat. Make the mousse: beat the egg yolks with the sugar for 2 minutes. Mix in the warm melted chocolate, stirring with a wooden spatula. Whisk the softened butter with the powdered cocoa. Pour onto the egg yolk-chocolate mixture. Beat the cream stiffly, adding the confectioner╒s sugar. Pour into the mixture, beating thoroughly with the whisk. Moisten the sponge fingers with the cold coffee. Use to cover the bottom and the sides of a Charlotte mold. Fill the mold with the mousse. Put into the refrigerator for at least 3 hours. Meanwhile, make the coffee sauce: Sieve the milk. Work the egg yolks with the sugar until white. Add the flavored milk, stir, pour into a saucepan and cook over a low heat, stirring continuously until the sauce coats the spoon. Leave to cool. Turn out the Charlotte onto the serving dish, surround with a little sauce, serve the remaining sauce in a sauceboat.
