1. If starting from a fresh pumpkin: Use a "sugar pie pumpkin" or "pie pumpkin" and not a decorative jack-o-lantern type pumpkin. Preheat oven to 350* F. Wash the outside of the pumpkin well. Cut off the stem of the pumpkin, and then cut in half vertically. Remove the seeds and strings. Rinse and save the seeds for drying and replanting and/or roasting. Place the two halves of the pumpkins on a baking pan lined with a piece of foil that is twice as long as the pan. Fold the foil over the top of the pumpkins and bake for 75 to 90 minutes, or until soft.
Allow pumpkins to cool (they can be refrigerated over night.) Peel off the skin, and any overly browned parts.
Place the flesh of the pumpkin in a food processor or good blender and puree until smooth.
Leave the pumpkin in the processor or blender, and add the rest of the custard ingredients.
An average sized pumpkin makes about 2 cups of pureed pumpkin. A little more or a little less is fine.
2. Nutrition figures are for 8 servings. I made 6 large custards, and we felt full after half, so it could easily serve 12. I split the difference and calculated for 8. Nutrition is also for the custard as written, and does not include streusel or whip cream topping.
3. Streusel recipe
here.