Heat oven to 350°F and arrange a rack in the middle. Heat 2 tablespoons olive oil over medium heat in a large, deep frying pan. Add 1 large diced onion and season with salt and pepper to taste. Cook, stirring occasionally, until the onion starts to soften, about 5 minutes.
Add 8 ounces chorizo and 3 chopped garlic cloves. Cook, breaking up the sausage with a wooden spoon, until the chorizo blends with the onion (it won't brown), about 5 minutes.
Add 1 1/2 cups basmati or other long-grain rice and 3 cups chicken broth. Bring to a boil, scraping up any browned bits stuck to the bottom. Reduce the heat to a low simmer, cover, and cook until the rice has absorbed most of the liquid, about 10 minutes. The rice will still be slightly firm, but it will finish cooking inside the pumpkin. Remove from the heat and let cool slightly.
While the rice cools, carefully cut the top off the pumpkin or winter squash as you would when carving a jack-o'-lantern. Save the top to use as a lid. Scrape out the seeds and stringy pulp, discarding them or saving the seeds for roasting. Rub a little olive oil inside the squash and season the inside of the pumpkin with salt and pepper to taste.
Once the rice has cooled slightly, fold in 4 ounces goat cheese, 1/3 cup raisins, and 1/2 cup cream. Taste the filling and adjust the salt and pepper if necessary. Pack the rice mixture fairly tightly into the pumpkin. Depending on its size, you may have some filling left over.
Place the stuffed pumpkin on a parchment- or foil-lined baking sheet or in an oven-safe frying pan large enough to hold it.
Roast for approximately 2 hours, until the filling is bubbling and the pumpkin flesh is easily pierced with a fork.
Remove the pumpkin from the oven, let cool at least 10 minutes and cut into wedges. Garnish with thinly sliced scallions and serve with lemon wedges for squeezing over the top.
