Roll out the pastry thinly, cut into rectangles 9x1 cms, brush with egg and bake . When cooked, slice each piece horizontally . Wash and cut the leeks "en julienne". Sweat the leeks and one of the chopped shallots in the butter. Season with salt, pepper and cayenne. Add the cream and simmer for 3 minutes to reduce the liquid. Chop the livers, season with salt and pepper and saute with 25 g clarified butter and the remaining shallot. Deglaze the pan with the Cognac. Fill the puff pastry slices with a layer of the very hot leeks then a layer of the sauteed livers. Garnish with chopped chives.