Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (2024)

Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (1)

By: Becky Hardin

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French Onion Soup Casserole is the perfect combination of a classic soup and an easy casserole recipe. This delicious French Onion Casserole is filled with caramelized onions, crunchy baguettes, and plenty of cheese. It tastes just like the soup, but in an easy to make weeknight dinner! I love this easy French Onion Soup Casserole!

Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (2)

Table of Contents

Easy French Onion Soup Casserole

What do you get when you combine classic french onion soup with an easy casserole recipe? Easy French Onion Soup Casserole!

French Onion Soup is such a classic, and for good reason. The mixture of flavors is just perfect, and it always feels like such a special treat. I love the slightly sweet yet savory taste of the soup, with croutons and cheese on top. Yum!

Since I’m a fan of easy meals, of course I’m obsessed with casseroles. I wanted to take those amazing flavors from the soup and turn it into an easy casserole recipe that can be made any night of the week! This Easy French Onion Soup Casserole turned out so perfectly, and I think it’s even more crave-worthy than the soup.

You get the delicious caramelized onions, the crispy baguette slices, and lots of cheeeese all mixed together into one dish. I absolutely LOVE this French Onion Casserole!

This easy French Onion Casserole recipe is the perfect blend of flavors!

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French Onion Casserole Recipe

What’s not to love about this recipe? An easy french onion soup recipe in the form of an easy to make casserole dish that the whole family will love! Easy, easy, easy (and SO tasty).

Take all of the ingredients and things you love about French Onion Soup, and put them in thus french onion casserole. You get the onions, the crunch, and the cheese! It’s easy to dig in and get the perfect bite with all the flavors melted together.

French Onion Soup Casserole Ingredients:

  • Vidalia Onions
  • Yellow Onions
  • Baguette Slices
  • Thyme
  • Bay Leaf
  • Beef Broth
  • Chicken Broth
  • Gruyere Cheese
  • Dry Sherry
  • Butter
  • Salt & Pepper
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How to Make French Onion Casserole

Gather up your ingredients and start making this amazing French Onion Casserole. You can make parts of this recipe ahead of time to help cut down on cook time. The onions can be made up to 3 days ahead, and the baguette slices can be made up to 5 days ahead. That way you can just jump in and bake the casserole when you get home from work and you’re ready to eat!

How to Make French Onion Soup Casserole:

  1. Bake the baguette slices in the oven at 400°F for 8-10 minutes.
  2. While the bread is toasting, add butter, sliced onions, salt & pepper, thyme and bay leaf into a prepared dutch oven. Remove toasted bread from the oven when it’s done.
  3. Place the lid on the dutch oven and cook the onions in the oven at 400°F. After 1 hour, stir the onions and then place them back in the oven, with the lid slightly ajar. Cook another hour.
  4. Now removed the onions from the oven and stir. They should be a dark brown. Cook another 30 minutes if they don’t seem dark enough. You really want to get a nice caramelized flavor out of them.
  5. Transfer the pot of onions to the stove top, and place over medium high heat. Remove the bay leaf.
  6. Add in the sherry, beef broth, and chicken broth. Bring the mixture to a boil, stirring constantly, for about 4-5 minutes until it has thickened.
  7. To make the casserole, layer half of the baguette slices into the casserole dish. Then spoon the onions over each bread slice, and top with the remaining slices. Sprinkle the cheese over everything.
  8. Cover the casserole dish with foil, and bake for 30 minutes at 400°F.
  9. After that, remove the foil, switch the oven to broil, and broil the casserole for about 3 minutes to make the cheese bubbly and golden brown.

Be sure to check the recipe card below for more detailed instructions and the full recipe.

Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (7)
Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (8)

Easy French Onion Recipes

French Onion Soup is good, but I’m a fan of french onion everything. This French Onion Casserole is a new favorite, but I’ve got plenty of other recipes with these amazing flavors! Try my One Pan French Onion Chicken Skillet for the perfect easy chicken recipe. Or make these Mini French Onion Dip Bread Bowl for a fun party appetizer.

Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (9)

I can’t wait for you to try this easy French Onion Soup Casserole because I just know you’ll love it! Make this French Onion Casserole for a delicious dinner and enjoy!

See the recipe card below for details on how to make French Onion Casserole. Enjoy!

If you like this recipe, try these other easy casserole recipes!

  • Garlic Bread Pizza Casserole
  • King Ranch Chicken Casserole
  • Chicken Pot Pie Casserole
  • Cheesy Chicken and Rice Casserole
  • Beef Stroganoff Casserole
  • Enchilada Stuffed Pepper Casserole

Recipe

Easy French Onion Soup Casserole

4.67 from 66 votes

Author: Becky Hardin

Prep: 10 minutes minutes

Cook: 3 hours hours 15 minutes minutes

Total: 3 hours hours 25 minutes minutes

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Serves6 bowls

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French Onion Soup Casserole is the perfect combination of a classic soup and an easy casserole recipe. This delicious French Onion Casserole is filled with caramelized onions, crunchy baguettes, and plenty of cheese. It tastes just like the soup, but in an easy to make weeknight dinner! I love this easy French Onion Soup Casserole!

Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (11)

Email This Recipe

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Ingredients

  • 16 ounces baguette cut into ¼-inch slices (1 loaf)
  • ¼ cup unsalted butter (½ stick)
  • 2 Vidalia onions halved and cut top-to-bottom into ¼-inch-slices
  • 3 yellow onions halved and cut top-to-bottom into ¼-inch-slices
  • 1 teaspoon kosher salt
  • ½ teaspoon freshly ground black pepper
  • 5 fresh thyme sprigs leaves removed
  • 1 bay leaf
  • ½ cup dry sherry
  • 1 cups unsalted beef broth
  • 2 cups unsalted chicken broth
  • 8 ounces freshly shredded Gruyere cheese (about 2 cups)

Recommended Equipment

Instructions

  • Preheat oven to 400°F and set the oven rack to the lower-middle position. Spray a 9×13-inch baking dish with nonstick cooking spray and set aside.

  • Place the baguette slices on a metal rack placed inside a baking sheet and bake for 8-10 minutes or until golden brown. Remove from the oven and set aside until ready to use.

    16 ounces baguette

  • While the bread slices toast, generously spray the inside of a large Dutch oven with nonstick cooking spray. Slice the onions (if they haven’t already been sliced).

    2 Vidalia onions, 3 yellow onions

  • Add the butter, sliced onions, salt, black pepper, thyme leaves and bay leaf to the Dutch oven.

    ¼ cup unsalted butter, 1 teaspoon kosher salt, ½ teaspoon freshly ground black pepper, 5 fresh thyme sprigs, 1 bay leaf

  • Once the baguette slices have toasted, cover the Dutch oven tightly and cook the onions 1 hour. Remove pot from oven and stir, being sure to scrape the sides and bottom of pot.

  • Return the pot to the oven with the lid slightly ajar and continue cooking another 1 hour.

  • Once again, remove the pot from the oven and stir the onions (scraping the sides and bottom). The onions will be soft and a little darker than golden brown. If the onions need more color, return the pot to the oven (still with the lid slightly ajar) and cook another 30 minutes.

  • Transfer the pot to the stovetop and turn the heat to medium-high. *Remember – the pot is HOT! Use oven mitts when touching the handles.*

  • Remove and discard the bay leaf from the onions.

  • Add sherry, beef broth and chicken broth; bring to a boil, stirring constantly, until slightly thickened, about 4-5 minutes.

    ½ cup dry sherry, 1 cups unsalted beef broth, 2 cups unsalted chicken broth

  • Layer half the toasted baguette slices in the prepared casserole dish.

  • Spoon onion mixture evenly over the bread, and top the remaining bread slices.

  • Sprinkle with shredded cheese and cover with foil.

    8 ounces freshly shredded Gruyere cheese

  • Bake at 400°F for 30 minutes.

  • Set the heat to broil and remove the foil.

  • Broil 3 minutes or until cheese is bubbly. Watch closely.

  • Garnish with additional thyme leaves, if desired.

Last step! Don’t forget to show me a pic of what you made! Upload an image or tag me @thecookierookie on Instagram!

Becky’s tips

  • The baguette slices can be made up to 5 days ahead and kept in an airtight container until ready to use.
  • The caramelized onions can be made up to 3 days ahead and kept refrigerated, in an airtight container, until ready to use.

Storage:Store leftover French onion soup casserole in an airtight container in the refrigerator for up to 4 days.

Nutrition Information

Serving: 1bowl Calories: 510kcal (26%) Carbohydrates: 52g (17%) Protein: 22g (44%) Fat: 23g (35%) Saturated Fat: 13g (81%) Polyunsaturated Fat: 2g Monounsaturated Fat: 6g Trans Fat: 0.3g Cholesterol: 62mg (21%) Sodium: 1235mg (54%) Potassium: 508mg (15%) Fiber: 4g (17%) Sugar: 12g (13%) Vitamin A: 638IU (13%) Vitamin C: 11mg (13%) Calcium: 508mg (51%) Iron: 3mg (17%)

Did You Make This?I want to see! Be sure to upload an image below & tag @thecookierookie on social media!

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Easy French Onion Soup Casserole Recipe - The Cookie Rookie® (2024)

FAQs

How do you deepen the flavor of French onion soup? ›

A few sprigs of thyme and a bay leaf elevate the soup even more, but I take it a step further, adding a splash of fish sauce for complexity and depth—don't worry, it won't taste fishy—and a hit of cider vinegar to balance some of that oniony sweetness.

Why do you put baking soda in French onion soup? ›

The caramelized onions for this soup cook more quickly due to a pinch of baking soda but still have that deep, slow-cooked flavor.

How to reheat French onion soup in the oven? ›

Bake at 350 degrees for 10 to 15 minutes, watching to make sure they brown but don't overcook. Remove from oven, cool. To serve, ladle soup into ovenproof soup bowls. Top with 1 or 2 slices of toasted bread, sprinkle on cheese to cover and broil until cheese is melted and bubbly around edges, about 3 to 5 minutes.

How do you thicken French onion soup without flour? ›

You can also use cornstarch if you don't have any flour.

How to doctor up canned French onion soup? ›

Infusing the soup with a richer taste is as easy as quickly sauteing crushed garlic before pouring the soup in. Some soft, buttery garlic sauteed in earthy olive oil is the perfect addition to enrich canned French onion soup.

Why is my French onion soup so bland? ›

If you don't add enough salt, pepper, or other herbs and spices, the soup may taste bland.

Why do you put lemon juice in soup? ›

In this case, however, the lemon provides more of a flavor undertone that enhances other seasonings like thyme, parsley, and turmeric. According to trained chef Leetal Arazi, who spoke with Real Simple, you can bring a "zesty flavor" to your soup simply by adding lemon.

Is French onion soup good for you? ›

Well, you'll be pleased to know that french onion soup is, in fact, a highly nutritious choice. Onions, as part of the Allium family, contain Quercetin which is a powerful anti-inflammatory and should not be overlooked as a vegetable when considering your daily 7-a-day.

Does French onion soup get better the longer you cook it? ›

“If you're willing to put in the work to make French onion soup the traditional way,” as in several hours, “it does develop different flavors,” López-Alt told me. They're not necessarily flavors that are better or worse than with the quicker approach.

Can you eat French onion soup the next day? ›

Generally speaking, leftovers including soup can last in a fridge that's set at 40 degrees Fahrenheit for three to four days. If you don't think you'll finish it within that time frame, freeze it instead.

How thick should onions be cut for French onion soup? ›

Peel each half, keeping the flesh tethered at the root end. Slice 1/4-inch thick longways, pole-to-pole, using a mandolin if you have one.

How do you add depth to French onion soup? ›

Fix a bland onion soup by using supermarket broth and mild white onions, tasteless oil for sauteeing, stale plain white bread instead of croutons, and mild white cheese. Start by reducing the broth. Simmering out some water will intensify the flavor of the broth. Once you get it to the right point, add some salt.

Why add flour to French onion soup? ›

Sprinkle flour over and stir into onions, if you do not eat gluten you can omit. This step gives onion soup a bit more depth and body. Add red wine, chicken stock or water, thyme, and bay leaf and simmer for 30 minutes. You can cook the soup this far and save for another day.

Can you add milk to soup to make it creamy? ›

Milk or Half-and-Half: This is the other magical ingredient that turns your homemade chicken noodle soup into the creamiest soup ever. Use 1 cup of whole milk or 1 cup of half-and-half. If you want to make regular (non-creamy) chicken noodle soup, replace the milk with more chicken broth.

How do you add depth of flavor to soup? ›

Perk up a Bland Soup With Simple Pantry Staples

Add a splash of vinegar (any kind!), or a squeeze of citrus. Chances are, you could use a little more salt. Go ahead—it's ok. Salt perks up flat flavors and helps balance out bitter-tasting ingredients.

Why do you add flour to French onion soup? ›

Onion soup, at its very essence, is nothing more than onions and water boiled together. Period, done, finished, everything added from that point on is pure opinion. Caramelizing the onions brings out sugars, and makes a more luxurious silky and sweet soup, adding flour gently thickens and provides body.

How do you balance onion flavor in soup? ›

Adding a touch of acidity, such as lemon juice or a splash of vinegar, can help cut through the richness of the onions. Additionally, adding sweeter ingredients like carrots, bell peppers, or even a pinch of sugar can help counterbalance the strong taste.

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