In a large saucepan, combine the stock with the butternut squash and the parsley and sage sprigs. Bring to a boil, then simmer over low heat until the squash is tender, about 20 minutes. Discard the parsley and sage sprigs. Working in batches, in a food processor, puree the squash with about 1/2 cup of the stock. Return the puree to the sauce-pan, add the reserved sweet dumpling squash flesh and stir to combine. Season with salt and pepper. Keep warm.