Preheat oven to 350.
Mix together the cinnamon, nutmeg, ginger and cloves in a small bowl.
Heat 1 1/4 c. whipping cream and milk in a saucepan over medium heat. Do not let boil. When the mixture begins to steam, remove from heat and whisk in the pumpkin puree and 1¼ t. of the spice mixture and vanilla. (the remaining spice is for the whipped cream).
Using a mixer, whip the yolks and sugar in a separate bowl until they become pale yellow and thick, approx. 4 minutes.
Add the warm pumpkin mixture in a slow steady stream to the egg yolks. Whisk continuously to combine and then whisk for an additional minute.
Carefully fill your jelly jars ¾ full. Place the six baking containers into a roasting pan. Fill the roasting pan with hot water to come up ½ way on the jelly jars. Bake on the center rack of the oven for 30-40minutes. The center will be slightly jiggly.
Let cool for 1 hour and place overnight in the fridge. They can be made ahead several days.