Tortellini with Pumpkin Alfredo Sauce

Kosher salt

cheese tortellini

unsalted butter

small shallot, finely chopped

canned pure pumpkin puree (not pumpkin pie filling)

freshly grated nutmeg

heavy cream

grated Parmesan cheese, plus more for garnish

Freshly ground black pepper

Chopped fresh Italian parsley, for garnish (optional)