Leftover soups belong in casseroles
allow me to share a few basics.
Bonjour!
Last month, not only did I go to Paris with Paris by Mouth, a company I've been working for since I returned from my time at Le Cordon Bleu in Paris, but I also started developing recipes for their fantastic newsletter, to which I am very honored to contribute. If you're not a subscriber yet, you should be.
While I'm bursting at the seams to spill all the juicy details of my Parisian days—every sight, bite, and too-good-to-be-true moment (hold onto your berets, I've barely had time to unpack!)…
I want to share what I've been eating on repeat since I arrived. First, let me start by saying that I created this French Onion Soup recipe for Paris by Mouth, which I am very biased to say it's a good one (but it is!).
Now I have more or less 200 liters of French Onion Soup stashed in my freezer (any fellow recipe developers here to relate?), and I've been making this leftover soup casserole on repeat. This casserole is the simplest thing, is utterly delicious, and not a single guest I've served it to has suspected that it's a dish my husband and I can't stand anymore (again, 200 liters).
It's the type of dish you can whip up with any leftover soup, but it truly shines with Onion Soup, thanks to its rich caramelized flavors. It's a real time-saver, cutting out the need to laboriously build flavors from scratch since they're already infused in the soup. And let's face it, you've already invested plenty of time caramelizing onions for that soup, so why not put it to good use?
What I'm going to enthusiastically talk about now isn't per se a recipe (the French Onion Soup above is a recipe, follow that!); it's just a collection of ideas, so please don't feel obliged to follow it—just get inspiration from it.
I'm a firm believer that pretty much anything that looks unappealing outside of a casserole will look pretty good inside one, especially if you cover it in cheese. I also don’t pay much attention to seasonality when it comes to firing up my oven. Winter or summer, I'll happily bake away any day of the year. Although, being from a tropical country, I sometimes ponder if my heat tolerance operates on a different level. There she goes, effortlessly off track.
So, you see, I might not be the best person to offer you eating guidance, since most of the time, I just eat whatever the heck I feel like eating (leftovers + leftovers + leftovers). So if you feel like this is not the time to bake a casserole, I'm sure a substack neighbor will have a better recipe for you (no hard feelings, I promise).
But if you are on my team, I also made a video to help you understand what I mean:
To keep it short and sweet because it's Sunday, after all, and my only goal is to offer you a dinner idea for this week, here are some general ideas—things that you should do most of the time:
Begin by reducing your soup (or any liquid) to at least half, then taste it. This will provide valuable insight into both the flavor and texture direction of your dish. Ask yourself: Is it adequately seasoned with salt? How about heat? Has it developed more sweetness (as in the case of Onion Soup)? Would a touch of balsamic or a squeeze of lime enhance its complexity? Consider adding a pinch of paprika for smokiness or the brightness of fresh herbs— and if so, what do you have on hand in the fridge? Sometimes, our fridge is bare, and that's alright. Move on.
*I used leftover Onion Soup and adjusted the seasoning with soy sauce and red wine vinegar. Also a sprinkle of chives after baked.Next, let's discuss the consistency of the base you've created. If your soup started out a bit chunky, your veggies or meat might have softened considerably, but that's perfectly fine for our ultimate goal here—after all, no one eats a casserole for its texture alone. However, it's important to assess whether there's enough sauce to adequately coat all the added ingredients. Consider whether you prefer your casserole to be on the drier or more soupy side, and think about how the amount of "sauce" will influence the overall mouthfeel and bite of the dish when combined with the other ingredients. What do you envision when you think casserole? You make all the decisions here. Isn't that wonderful?
*I added a bit of dry vermouth to make my sauce more pourable.Now, think about "the filling". Is it shredded meat? More veggies? Starches? Beans? Again, open your fridge (and cabinets). Anything will work, and when I say anything, I mean anything! I once made a casserole with shredded cabbage, tomato soup, Marsala sautéed mushrooms, and crumbled Gorgonzola cheese—all leftovers, and let me tell you, it was outstanding (I know it's a hard sell, but I need you to believe me here). You also need to consider the ratio here and ask yourself, “Do I have enough sauce to cover all of this?” For example, if you're using leftover rotisserie chicken (which can be a bit dry), you'll need more sauce, butter, or a little bit of milk/stock/wine to keep things interesting. Ask your ingredients which direction you are going together, and they will hold your hands and take you there (if you ask kindly enough, of course).
*I used shredded roast chicken and cannellini beans.Lastly, toppings—which to me is always cheese. Just because I like it. There are no rules, you guys.
Be creative! Croutons, panko, slices of bread, toasted cassava flour, chopped nuts, crumbled bacon, slices of ham, cottage cheese, a creamy mix of yogurt + eggs, tiny dried shrimp, sliced hard-boiled eggs (why not?). If you have parmesan handy, it's always good to add a sprinkle of it. I always have the grated cheap one that comes in a tube that apparently everyone in the food world seems to hate. I find it lovely for these types of things, and it's so practical (have you ever grated a big block of fancy aged parmesan with a Microplane?), and incredibly inexpensive. Cooking in real life is not all about glamour, surprisingly.
*I used cubed super old bits of bread I found in my pantry, toasted with a bit of olive oil and dried oregano. I always toast croutons with dried oregano—the Italian kind, not the Mexican.*When it comes to cheese, I always experiment with unusual ones. I love discovering new cheeses in the supermarket, buying them to find out they're dreadful to eat on their own, but then discovering how wonderfully they work in a casserole! Save them all in a ziplock bag in the back of the cheese drawer in your fridge—the more bits, the better.
*I used Gruyère because I had so much, and a really bad cheddar. It was fine.
Then, bake it in a preheated oven at a very high heat, ideally at least 400°F. As for the cooking duration, I wouldn't know. My cues are (and yours should be too): wait for at least 20 minutes, as rarely anything will be ready in less time. Look for a golden bronzed/caramelized/toasted appearance, ensuring the cheese (if using) has melted. Keep an eye out for bubbles forming around the edges, indicating a different texture of the sauce, somewhat more uniform in consistency. And, of course, trust your senses—if it smells heavenly, it's likely done. Remember, the cooking time may vary significantly depending on the size of your casserole dish. Use your good judgment and make mental notes for future reference (I never do, but you should!)
A little note on bakeware:
Glass Baking Dish (such as Pyrex): These are popular because they allow for even heat distribution and are transparent, so you can monitor the cooking process.
Ceramic Baking Dish: Similar to glass, ceramic dishes also distribute heat evenly and come in various sizes and shapes.
Metal Baking Pan: Metal pans, such as stainless steel or aluminum, are durable and conduct heat well.
Cast Iron Skillet or Dutch Oven: These heavy-duty pans are excellent for baking casseroles, as they retain heat effectively and can go from stovetop to oven.
Disposable Aluminum Pan: If you're looking for convenience or bringing a casserole to a potluck, disposable aluminum pans are an option. However, they may not provide as even heat distribution as other types of bakeware.
You can even use pots to bake casseroles. Just ensure that the pot is oven-safe at the temperature required for your recipe, and you should be good to go.
Ultimately, the best choice depends on personal preference and what you have available in your kitchen.
To me, proficiency in the kitchen comes down to practice, a dash of intuition, learning from mistakes, and celebrating successes. Some of your leftover soup casseroles will turn out amazing, while others might be a disaster, but it's important to value them all as part of the learning process. Consider each attempt as a rehearsal for something bigger.
One day, you'll find yourself experimenting with more daring ingredients and creating surprising flavor combinations effortlessly. You'll even catch yourself brainstorming recipe ideas while grocery shopping—an unmistakable sign of a good cook! And believe it or not, you may start intentionally making extra soup just to ensure you have leftovers.
It will be a success. I have confidence in you!
Would you tell me in the comments what are you cooking this week?
Bon appétit!
See you in a few days, talking all things Paris!
That casserole looks super yummy!