Cream the butter and sugar in a bowl, beat in the eggs and vanilla. Sift the flour with the baking powder and salt, then gently knead in the butter mixture until a soft dough is obtained. Chill before using. To prepare the filling, chop the figs into small pieces and put them in a bowl. Mix in the tangerine zest and liqueur then cover with enough boiling water to cover. Cover with cling film and when the liquid is absorbed and the figs are soft, whizz them in a food processor. Allow to cool down completely before mixing in the dark chocolate and walnuts. Roll the sweet pastry into a long strip spread the filling length wise on the side of it. Lap the pastry over and roll, press gently to firm tightly. Brush the roll with a beaten egg and sprinkle with sugar. Cut into desired shapes and bake for 15 minutes in a hot oven at 200`c. Meanwhile, prepare the hot chocolate. Melt the white chocolate together with the milk over gentle heat in a small pan. Whip the fresh cream together with the cocoa powder. Pour the liqueur in the hot chocolate and pour the mixture into serving glasses. Top with the chocolate whipped cream and serve with the fig rolls.