French Onion Chicken Casserole
This post may contain affiliate links. See my disclosure policy.
My French onion chicken casserole recipe is what I turn to when I want to serve my partner or family a warm, hearty dinner that captures the best parts of classic French onion soup. I pack it with caramelized onions and juicy chicken, all baked in one dish.
I’ll be honest- I’m not the biggest fan of casseroles. I think it stems from my growing up with the same casseroles over and over again. This is probably why I set out to develop one that was inspired by my favorite soup- French onion. To make it a little more satisfying, I start with a base of pan-fried chicken breast pieces. I then toss it with the caramelized onions and transfer it to a baking dish, along with some chicken broth to keep everything moist. The fun part is topping it with baguette slices and plenty of cheese. It sounds fancy, but it’s a one-dish dinner that works as an easy weeknight meal or for entertaining guests.
Table of Contents
Arman’s recipe highlights
All the textures! You get tender, juicy chicken, crispy, soaked baguette slices, and gooey cheese. This is the epome of a great casserole.
Fancy without fuss. I always get rave reviews whenever I make this for guests or visiting family. Everything is baked in one pot, and when you break it all down, it’s just a handful of ingredients.
No canned soup. Many French onion casserole recipes call for canned soup- not mine (sorry- I try to avoid it when I can). My version uses upgraded flavors, thanks to a chicken-broth-based sauce made from scratch.
Key Ingredients and Tips
- Chicken breast. Boneless, skinless breasts are chopped into bite-sized pieces. If you don’t have chicken breasts at home, I’ve sometimes used boneless, skinless chicken thighs instead.
- Herbs and spices. I use salt, pepper, dried thyme, and paprika to season the chicken and give every piece an indulgent, warm flavor.
- Butter. To prevent the chicken and onions from sticking in the pan, it also adds some richness.
- Onions. French onion soup is typically made with yellow onions, but almost any variety of onion will work. You can even use shallots if you have them on hand.
- Balsamic vinegar. This adds a sweet, acidic flavor that cuts through the other rich flavors.
- Garlic. Freshly minced cloves, please. It just won’t have the same effect with powdered garlic.
- Chicken broth. Use a good-quality stock for the most comforting flavor. I try to find brands with the fewest ingredients. My go-to is Swanson 100% Natural Chicken Broth.
- French baguette. To cover the casserole and add a buttery crunch to each bite, just like in traditional French onion soup. Try to use a fresh baguette, as day-old bread will be too hard (yes, even when soaked in the broth).
- Gruyere cheese. This is a classic cheese choice for French onion-inspired dishes. Provolone or Swiss cheese also works well. Please shred the cheese by hand- the pre-shredded options have anti-caking agents in them, which prevent them from melting properly.
How to make
I’ve included step-by-step photos below to make this recipe easy to follow at home. For the full printable recipe instructions and ingredient quantities, scroll to the recipe card at the bottom of this post.
Step 1- season: Cut the chicken into bite-sized cubes, then season them with salt, pepper, thyme, and paprika.
Step 2- Cook the chicken in a hot, buttered skillet until the pieces have browned. Transfer them to a baking dish.
Step 3- caramelize the onions: Add more butter to the skillet, then add the onions and cook until caramelized. Afterward, add in the balsamic and garlic.
Step 4- assemble and bake: Pour the onions over the chicken in the baking dish. Pour the chicken stock over top, then cover with the toasted baguette slices and grated cheese. Bake the casserole until the cheese is melted.
Pro recipe tips
- Slowly caramelize the onions. When done properly, this step can take between 10 to 15 minutes. Just be patient… You want to achieve that deep, caramelized flavor because it adds the timeless taste of French onion soup to this casserole.
- Rest before serving. Let the casserole rest for a few minutes after baking to help the flavors meld together and firm up the texture.
- Time-saving tips. Speed up the recipe by browning the chicken, caramelizing the onions, and shredding the cheese 1 to 2 days ahead of time. You can also shred a store-bought rotisserie chicken to save even more time.
- Prevent soggy bread. I found that adding sufficient cheese on top prevents the bread from becoming dry or brittle. If you are worried, remove the crust from the French stick/baguette.
Recipe variations
Add mushrooms. I sometimes sauté sliced mushrooms with the onions for extra flavor and texture. The longer cooking time will reduce the moisture that mushrooms typically lose.
Add bacon. Toss crispy bacon crumbles with the chicken and onions for an irresistible salty flavor and crunch.
Make it vegetarian. If I need to make this meat-free, I use either plant-based chicken or a medley of roasted vegetables, such as bell peppers, zucchini, onions, eggplant, potatoes, or carrots.
Lower the carbs. Cover your French onion chicken casserole with a low-carb bread substitute, such as toasted keto bread or keto rolls.
To make a gluten-free casserole, simply substitute the French bread for crusty gluten-free French bread. I like La Brea Gluten-Free French Baguette.
Storage and make-ahead
Once the casserole has cooled, I recommend covering it and refrigerating it for up to 3 days. Any longer, and the baguette will become too soggy. To reheat, add a portion to an oven-safe dish and reheat at 350°F for about 12-15 minutes.
If you want to make this casserole ahead of time, you’ll need to assemble it first. Then, cover the top with plastic wrap and aluminum foil and freeze for 2 months. Let it thaw overnight in the refrigerator and follow the baking instructions the next day.
More comforting casseroles
French Onion Chicken Casserole
Video
Ingredients
- 1 pound chicken breast diced into 1-inch pieces
- 1 teaspoon salt
- 1/2 teaspoon pepper
- 1/2 teaspoon dried thyme
- 1/2 teaspoon paprika
- 3 tablespoons butter
- 14 ounces onion thinly sliced
- 1 tablespoon balsamic vinegar
- 2 cloves garlic minced
- 1 cup chicken broth
- 8 slices baguette toasted and chopped
- 1 cup Gruyere cheese grated
Instructions
- Preheat the oven to 250C/475F.
- Season the chicken with salt, pepper, thyme and paprika.
- Heat half of the butter in a skillet, and once hot, add the chicken. Cook until it changes color and set aside.
- Add the rest of the butter to the skillet and add the onion. Cover with a lid and cook, stirring occasionally, until the onions are softened, around 5-7 minutes. Pour in the balsamic and garlic and cook for 1-2 minutes.
- Transfer the onions to a baking dish, combine with the chicken, and pour chicken stock over it. Cover the casserole with the toasted baguette pieces, followed by grated cheese.
- Bake for 5-10 minutes or until the cheese melts and serve warm.
Chicken broth? Or chicken stock? Ingredients list states broth. Cooking instructions States stock.
TANX -G
Hi Gail- either or. 🙂 I’ll amend the post for it to say broth throughout, but stock works just the same 🙂
My husband has never liked onions until this recipe!!! We both loved it. I used gluten free bread (toasted) for my portion. Definitely adding this to the rotation.
I love to hear that, Emily. Thanks for taking the time to leave a lovely review and rating 🙂
So French people eat like this usually? I never tried French recipes.
What a good and refreshing ingredients. It sounds much tasty with lots of cheese?
Has anybody actually frozen this casserole and then cooked later? I would like to make this for a sick friend but I want to make sure that it’s not watery or that the bread isn’t sloppy once thought and cooked.
Hi Erin- Provided you quickly wrap it once it is assembled, it will keep well. I don’t recommend baking it then freezing.
This was excellent! Thank you.😊
First time making this and we enjoyed it very much. I didn’t add the baquette since I am gluten free – I should have made some rice to serve it over. Easy to make for a quick dinner.
I toasted some gluten free bread & used that & it was delicious!
I have read the recipe a couple of times but I can’t see how long the dish has to be in the oven for? Am I missing something?
5-10 minutes.
Thank you! Having read the full directions I can see the chicken has to be cooked through. I mistook the instructions to mean just until it had changed colour. Really looking forward to trying this, it looks delicious!!
Looks good-eager to try !
this is a lot like a casserole my mom makes with chicken, peppers and chicken, this is really alike so thanks
So welcome! 🙂
so far i have not had time to cook anything, but i am saving up the recipes for summer so i can have a comfort food cookin binge.