1. Preheat the oven to 180C/350F/gas mark 4.
2. Using a sharp knife, cut a lid off the pumpkin. Scrape out the seeds and threads inside and discard.
3. Rub the butter around the inside of the pumpkin and season generously with salt and pepper.
4. Place rice, shallots and garlic in the pumpkin. Add the thyme, rosemary and parsley.
5. Bring the milk to the boil and pour enough into the pumpkin to almost fill it.
6. Cover with its lid, then wrap foil loosely around it, taking care not to spill the contents. Stand it in a roasting tin and bake for 1¾-2½ hours until the inside is tender.
7. If you can find them, fish out the herb twigs, then stir the Parmesan into the soup, taste and adjust the seasoning. As you serve the soup, scrape out some of the softened pumpkin with each spoonful. Pass croutons around separately.
Exact cooking time depends on the size of the pumpkin, but if it seems to be almost done and you are not ready to eat, turn the oven down low to prevent the shell softening too much.