To streamline traditional onion soup, we eliminated the need for home-made beef stock and time-consuming caramelized onions. Instead, in this lighter-tasting version, we’ve used canned chicken broth and cut the onion cooking time by nearly half. Plus, it’s even better if made a few days ahead.
Soup will keep well, covered and refrigerated, up to 3 days or in the freezer up to 3 months. Cheese mixture can be made 3 days ahead as well, then wrapped and refrigerated. Baguette slices can be stored in an airtight container or sealed bag up to 3 days at room temperature. To reheat soup, cover and stir occasionally over medium-high heat until hot.