Recipe: French Onion Soup Casserole
If you’ve got leftover caramelized onions, or you are about to make a recipe that uses them, double up. And while you’re at it, grab that loaf of leftover bread because you are about to embark on a trip to France in one delicious vegetarian casserole based on the famous soupe à l’oignon gratinée.
Caramelized Onions Are a Leftover Rockstar
Caramelized onions are a result of that magical mixture of onions and time, cooked slow and on a low heat, so the onion’s natural sugars come forward and the onions become jammy. This recipe includes making caramelized onions for the base of the casserole, but I do my best to have some on hand almost all the time. Caramelized onions also keep, refrigerated, for about three days in a covered container, and can even be frozen.
A Mini Guide to Caramelized Onions
Stock: The Foundation Flavor in a Vegetarian Casserole
To stock or not to stock? That is the question raised by so many chefs and cooks when it comes to French onion soup’s base. Most onion soups are made with a beef stock, made from browned bones and plenty of vegetables and cooked ad infinitum. This recipe creates its own vegetable stock as you cook the ingredients. It takes less than half an hour and works as a wonderful, supportive base for the incredible caramelized onions. If you start the onions from scratch, assume it’s about an hour of cooking time.
The Joys of Day-Old Bread
Second-day bread is a kitchen wonder. This recipe puts that loaf of bread to full use — creating a mini-grilled cheese sandwich — all right on top of the casserole to soak into the deliciousness below.