In a saucepan, melt together the margarine, milk, sugar and salt. When the mixture starts to boil, add in the flour and mix to a paste. Lower the heat, and cook for a few minutes till the paste falls off the sides of the pan. Add the eggs, and beat thoroughly to a smooth paste. Leave to cool slightly before piping into small balls the size off a small walnut onto sheets lined with non-stick paper. Bake immediately in a hot oven at 220`c, for 20-25 minutes. The profiteroles will puff up in the oven and it is very important that you do not open the oven door before 20 minutes, otherwise they will collapse. When the profiteroles are golden brown in colour, remove them from the oven and allow to cool on a wire rack. Meanwhile, you can prepare the Chantilly cream filling. Whip the cream to stiff peaks in a medium bowl and gently fold in the orange zest, along with the cold custard or patisserie cream. Place the Chantilly cream in the fridge to chill while you prepare the chocolate sauce. Put the chopped chocolate in a bowl over pan of hot water and melt the chocolate. Add in the double cream and the orange liqueur and stir well. Set aside while you fill the profiteroles with the Chantilly cream using a piping bag. When the profiteroles are all filled, pile them up on a round serving dish and pour over the delicious warm chocolate sauce.