Preheat oven to 325 degrees F.
Whisk together cream, milk, syrup, and pumpkin in a heavy saucepan and bring just to a simmer over moderate heat.
Whisk together yolks, cinnamon, nutmeg, and salt in a bowl.
Add hot pumpkin mixture to yolks in a slow stream, whisking constantly. Pour custard through a fine-mesh sieve into a large measuring cup, then divide among custard cups (you may have some custard left over, depending on size of cups). Bake custards in a hot water bath pan covered tightly with foil, in middle of oven until a knife inserted in center of a custard comes out clean, 35 to 40 minutes. Transfer custards to a rack to cool completely. Chill, covered, until cold, at least 2 hours.
Cook's note: Pots de creme can be chilled up to 2 days.
Recipe courtesy of Gourmet Magazine