This isn't a soup, actually, it's more like a gratin baked right inside the pumpkin. I was 21, and I didn't care that it was incredibly rich. Today I mix the cream with chicken broth (about a cup and a half of cream to about a cup of broth). It's STILL pretty much of a heart-stopper but it's irresistible.
Another helpful hint: If you brush the outside of the pumpkin with oil, it will look better when it emerges.
Go out and buy a fairly small pumpkin with a flat bottom. Cut off the top, as if you were going to carve a jack-o-lantern, and hollow it out. Spread the seeds out and dry them to eat later.
Now get a good loaf of French bread, slice it and toast it lightly. Grate a goodly amount of one of the Swiss cheeses - Emmenthaler, Gruyere or Appenzeller (you'll need about 12 ounces). Layer the toast and cheese inside the pumpkin until it's almost full (leave a half inch on the top because the filling will expand a bit).
Mix 1 cup of chicken stock into a cup and a half of cream. Add a teaspoon of salt. Grind in some black pepper and grate in some nutmeg. Then fill the pumpkin almost to the top with this mixture, replace the top of the pumpkin and bake in a 350 degree oven for about 2 hours.
Bring the whole pumpkin to the table. When you serve it be sure to scoop out the pumpkin flesh with the cheese and the cream. Serve with a light second course.