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). Layer the toast and cheese inside the pumpkin until it's almost fill. Then fill the pumpkin up with cream. Add the salt, pepper and nutmeg, replace the top of the pumpkin and bake in a 300 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.