(Note: this is Dorie's narrative below, with my comments sprinkled in. The original recipe calls for bacon instead of sausage.)
Center a rack in the oven and preheat the oven to 350 degrees F.
Line a baking sheet with a silicone baking mat or parchment, or find a Dutch oven with a diameter that's just a tiny bit larger than your pumpkin. If you bake the pumpkin in a casserole, it will keep its shape, but it might stick to the casserole, so you'll have to serve it from the pot—which is an appealingly homey way to serve it. If you bake it on a baking sheet, you can present it freestanding, but maneuvering a heavy stuffed pumpkin with a softened shell isn't so easy. However, since I love the way the unencumbered pumpkin looks in the center of the table, I've always taken my chances with the baked-on-a-sheet method, and so far, I've been lucky. (Note: SoupAddict did the bowl method, which worked out really, really well, as the bowl was a perfect fit and was completely portable.)
Using a very sturdy knife—and caution—cut a cap out of the top of the pumpkin (think Halloween Jack-o-Lantern). It's easiest to work your knife around the top of the pumpkin at a 45-degree angle. You want to cut off enough of the top to make it easy for you to work inside the pumpkin. Clear away the seeds and strings from the cap and from inside the pumpkin. Season the inside of the pumpkin generously with salt and pepper, and put it on the baking sheet or in the pot.
Toss the bread, cheese, garlic, sausage, and herbs together in a bowl. Season with pepper—you probably have enough salt from the sausage and cheese, but taste to be sure—and pack the mix into the pumpkin. The pumpkin should be well filled—you might have a little too much filling, or you might need to add to it. Stir the cream with the nutmeg and some salt and pepper and pour it into the pumpkin. Again, you might have too much or too little—you don't want the ingredients to swim in cream, but you do want them nicely moistened. (It's hard to go wrong here.)
Put the cap in place and bake the pumpkin for about 2 hours—check after 90 minutes—or until everything inside the pumpkin is bubbling and the flesh of the pumpkin is tender enough to be pierced easily with the tip of a knife. Because the pumpkin will have exuded liquid, I like to remove the cap during the last 20 minutes or so, so that the liquid can bake away and the top of the stuffing can brown a little.
When the pumpkin is ready, carefully, very carefully—it's heavy, hot, and wobbly—bring it to the table or transfer it to a platter that you'll bring to the table.
To serve: You have a choice—you can either spoon out portions of the filling, making sure to get a generous amount of pumpkin into the spoonful, or you can dig into the pumpkin with a big spoon, pull the pumpkin meat into the filling, and then mix everything up. I'm a fan of the pull-and-mix option. Served in hearty portions followed by a salad, the pumpkin is a perfect cold-weather main course; served in generous spoonfuls, it's just right alongside the Thanksgiving turkey.
To store: It's really best to eat this as soon as it's ready. However, if you've got leftovers, you can scoop them out of the pumpkin, mix them up, cover, and chill them; reheat them the next day.
Other ideas: There are many ways to vary this arts-and-crafts project. Instead of bread, I've filled the pumpkin with cooked rice—when it's baked, it's almost risotto-like. And, with either bread or rice, on different occasions I've added cooked spinach, kale, chard, or peas (the peas came straight from the freezer). I've made it without bacon (a wonderful vegetarian dish), and I've also made it and loved, loved, loved it with cooked sausage meat; cubes of ham are also a good idea. Nuts are a great addition, as are chunks of apple or pear or pieces of chestnut.