Sift together two thirds of a cup of flour, one tablespoon sugar and a pinch of salt. Beat together two whole eggs and two egg yolks and add them to the dry ingredients. Add one and three quarter cups of milk and stir together until smooth. Add two tablespoons of melted butter and one tablespoon of cognac. Let the batter stand for two hours before cooking the crepes. Make the crepes about, four inches in diameter and leave to cool. Place one teaspoon of creme fraiche or sour cream in the centre of the crepe, a little finely chopped onion and one teaspoon of caviar. Form into a bundle, tie with a chive and serve.