I named this soup a chowder because it's full of chunky vegetables and has a thick consistency from the addition of cornmeal. However, it is much lighter than cream based chowders as it is dairy- and gluten-free.
1Heat a medium-large cast iron pan over medium heat for 4 minutes. You should not see wisps of smoke, but it should be very hot.
2Add the oil, it should shimmer in the pan.
3Add the pieces of squash in batches with a sprinkle of salt, not crowding the pan, and brown, 2-3 minutes each. Once browned, set pieces aside in a container while you finish the other batches. Continue with all the squash and celeriac.
4Add the carrot and onion and saute until beginning to soften, 3-5 minutes. Add the broth and bring to a simmer.
5Sprinkle in the corn meal slowly, stirring constantly. Return the squash and celeriac to the pan, along with the salt. Simmer 20 minutes, stirring occasionally and scraping the bottom of the pan, until the cornmeal is no longer crunchy and the squash is tender. Taste for salt, adding as needed.
6Serve hot with chopped celeriac leaves and roasted chickpeas.