Crush the chocolate into smithereens in the food processor. Heat the cream and milk until just about boiling, add the vanilla and allspice and pour through the funnel over the chocolate. Let stand for 30 seconds. Process for 30 seconds, then crack the egg down the funnel and process for 45 seconds.
Pour into whatever little cups you're serving in, and sit them in the refrigerator for 6 hours or overnight. But remember to take them out of the refrigerator a good 20 minutes before you want them to be eaten; the chill interferes with their luscious, silky richness.
This makes 2 cups altogether: enough to fill 8 little pots of approximately 1/4 cup capacity. But if you've got only bigger cups, just augment quantities.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.
Recipe courtesy of Nigella Lawson, 2007