Whisk the yolks and scraped vanilla bean with sugar for half an hour (in a food processor for 10 min) until the sugar has dissolved and the mixture is thick and creamy. While continuing to whisk, gradually add the cognac or brandy. Let stand for a few minutes, then stir repeatedly. Pour into a nicely shaped bottle and cork. Shake well before use. Egg cognac is ready to drink on the spot **.