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Crusty French bread topped with melted cheese and sitting in a sweet onion broth…this French Onion Soup Casserole is a must-serve side dish or easy vegetarian dinner for all of your cozy gatherings this season!
Don’t you just love a good bowl of French Onion Soup? This casserole takes all of those delicious flavors and bakes them into an easy dish that can be served alongside your favorite roasted turkey, grilled steak, pot roast, fresh seafood, or baked chicken.
It pairs beautifully with just about any main course, it’s easier to prepare than individual bowls of soup, and the rich broth base you cannot beat!
Add Chicken, Sausage or Beef!
If you want to make this dinner a true one-dish meal, you can add cooked chicken, sausage, or ground beef into the soup base when you transfer the mixture to the baking pan.
It’s also a lovely vegetarian main course option with a salad alongside for some leafy green freshness!
Prepare this Casserole in Advance
While the cook time is longer than my normal quick-prep recipe, it’s super easy and it only requires about 10 minutes of actual hands-on time.
I like to prep the French Onion Soup base for the casserole in advance (up to a day or two ahead of time), so that when I need to pop it in the oven on a busy weeknight everything is ready to go!
How to Make French Onion Soup Casserole
- Melt butter in a large saucepan over low heat.
- Add onions and cover. Cook for about 30 minutes, stirring occasionally.
- Add the beef broth and the Worcestershire sauce. Heat the broth mixture until it boils.
- Reduce heat to low. Allow to simmer, uncovered, for about 30 minutes. The broth will reduce.
- Pour onion and broth mixture into a medium greased casserole dish (you can use a 1 ½-quart baking dish, an 11×7-inch baking dish, a 9-inch square baking dish, or something similar in size). Lightly toast the slices of bread.
- Place toasted bread in a single layer on top of onion/broth mixture.
Cover bread with a thick layer of the shredded mozzarella and top with grated Parmesan. - Bake, uncovered, in a 350F oven for 20-30 minutes, or until cheese is melted and brown on top.
I hope that you enjoy this versatile, cozy, and incredibly rich dish just as much as my family does!
Top Tips for Making French Onion Soup Casserole
- Cooking the onions for 30 minutes may seem long but this is what gives your casserole the beautifully rich, French onion soup flavor so don’t rush this step.
- No mozzarella? You can use another good melting cheese such as gruyere or fontina. You could also use white sharp cheddar.
- Any white crusty bread would work well for the topping.
- I recommend using beef broth for an authentic flavor.
- You can add meat such as chicken or sausage for extra protein.
- You can easily prep this dish in advance, see notes below!
More Delicious Casseroles You Might Like:
- Dump-and-Bake Chicken Stuffing Casserole
- Dump-and-Bake Chicken and Mushroom Casserole
- Easy Broccoli Casserole
- Apple and Butternut Squash Casserole
French Onion Soup Casserole
Ingredients
- 3 medium sweet onions, sliced
- 3 tablespoons butter
- 4 cups beef broth
- 1 teaspoon Worcestershire sauce
- 4 oz French baguette bread, sliced about ½-inch in thickness (approximately 10-12 small slices)
- 1 cup (4 ounces) shredded mozzarella cheese
- ¼ cup grated Parmesan cheese
Instructions
- Melt butter in a large saucepan over low heat.
- Add onions and cover. Cook for about 30 minutes, stirring occasionally.
- Add the beef broth and the Worcestershire sauce. Heat the broth mixture until it boils.
- Reduce heat to low. Allow to simmer, uncovered, for about 30 minutes. The broth will reduce.
- Pour onion and broth mixture into a medium greased casserole dish (you can use a 1 ½-quart baking dish, an 11x7-inch baking dish, a 9-inch square baking dish, or something similar in size).
- Lightly toast the slices of bread.
- Place toasted bread in a single layer on top of onion/broth mixture.
- Cover bread with a thick layer of the shredded mozzarella and top with grated Parmesan.
- Bake, uncovered, in a 350 degree oven for 20-30 minutes, or until cheese is melted and brown on top.
This looks delicious and so perfect for the cooler months ahead!
Thanks for visiting, Bianca! It really is the perfect side dish for the cooler months!
This looks great and I love how cleanup is a little easier with only 1 casserole bowl to soak and scrape instead of multiple little ones.
So true, Thao! The clean-up is MUCH easier. 🙂
Oh my word…these photos looks delicious! Heading on over to Red Lion to check it out asap!
Hi, Nicola! Thanks! 🙂
This looks awesome. Love French Onion Soup and this is a new twist. Thanks for sharing at What’d You Do This Weekend.
Linda
Thanks, Linda! And thanks very much for visiting!
I love French Onion soup, but haven’t made it because my oldest son doesn’t like onions…:-( Maybe I can make this and make him something else 🙂
Erlene, serve it on the side so that you can enjoy it…and let your oldest son eat the meat or other main course instead. Plus, I bet he’d love the bread and cheese part — even if he doesn’t love onions! 🙂
Yum, looks so good!
Thanks, Sharon!
I love the flavor of french onion soup…I know I will love this!! So glad you shared it with us at Foodie Fridays…I’m wishing I had some now!
This looks delicious! Thanks for linking up with SNF! Pinned to our party board!
Thanks so much for the pin, Jaren!
What a wonderful and tasty dish! Thanks for sharing!
Have a nice weekend!
Thanks, Mila! So glad that you stopped by. 🙂
I love French Onion Soup, so this looks incredible!!! Thank you so much for linking up at Tasty Tuesday! Your recipe has been pinned to the Tasty Tuesday Pinterest board! Please join us again this week!
This looks delicious, a great warming meal. Thanks for linking up to Sweet and Savoury Sunday, stop by and link up again. Have a great day!!
Thanks so much for visiting, Laura!
Love thie idea of getting the flavors of french onion soup in a casserole. Pinned. Thanks for bringing it by Weekend Bites.
Thanks so much for the pin, Diane! It’s definitely an easier way to accomplish the same flavors. 🙂
I know it would tast different w chic broth but don’t eat beef what do you think
Sure! I think that you can definitely make it with chicken broth. It will of course taste different, but it will still be good if you prefer chicken. 🙂
Se puede ptepsrar esta receta con bsde de sslsa nkanca???
Love the soup of this casserole! French onion soup is one of my favourite comfort foods so I can’t wait to try this!
How easy is it to serve at the table. Does anyone have pictures
I made this yesterday and loved it! It is delicioud!
Thanks, Janine! So glad that you enjoyed it!
Can this french onion soup casserole be frozen
Hi, Susan! Yes, I think that would work fine (either before or after baking). 🙂
This recipe was exactly what I needed to use up an abundance of onions. I had all the ingredients on hand. Thank you so much for a delicious dinner that was fun to make and enjoy. This dish is sweet and rich with simple ingredients. It doesn’t need any additional seasonings. I followed it as written. Yum!
Yay! So glad that it was a hit, Stacy! Thanks for letting me know. 🙂
Excellent soup and easy to make! Great for the winter.
Thanks, Robin!