Grease an eight-inch frying pan and heat. 

Mix all the ingredients with a hand blender to ensure the batter is smooth and free of any lumps. 

Spoon less-than one ladle full of batter into the pan and move the pan around until the batter coats the whole bottom of the pan. Turn over as soon as the batter has become one piece, or is light brown on the bottom side. Remove from the pan.

In a double boiler (a pot sitting on top of another pot that is filled with hot water) place sugar and water and cook until sugar dissolves.  Add the chocolate, cocoa and vanilla sugar and let melt, mix well.  Add yolks to mixture, mixing constantly until they are incorporated, add margarine. 

When smooth, pour into a container and let it sit uncovered until it has completely cooled.  Refrigerate or freeze.

Spread chocolate onto crepes using an offset spatula.  Fold crepe in half, then fold again. Serve with vanilla ice cream and toasted nuts.