When I was a kid, my very favorite soup was split pea soup. My mom would make it using the ham bone from Christmas dinner. Through the years, I’ve made my own split pea soup, sometimes with the Christmas ham bone for flavoring, and other times with smoked sausage.
I had about 3½ pounds of onions that needed to be used. Initially, I thought about making an onion tart, but 3½ pounds is really too much for one tart. The “master taste tester” suggested French Onion Soup.