French Onion Mac and Cheese + Video

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French Onion Mac and Cheese is a creamy baked casserole that is bursting with caramelized onion flavor. Make this recipe tonight for the best ever cheesy comfort food!

titled: French Onion Creamy Baked Mac and Cheese

French Onion Mac and Cheese

Combine two delicious comfort foods into one amazing dish with this French Onion Mac and Cheese recipe.

Bursting with all the flavor of the popular bistro soup, this cheesy baked pasta is sure to warm you up on the coldest of nights.

ingredients to make french onion mac and cheese

There are plenty of other delicious ways to enjoy caramelized onions too! My Slow Cooker French Onion Soup is not only easy to make, but it’s budget-friendly too.

You get so much flavor out of the onions, and don’t forget to top it with plenty of gooey cheese!

For a savory-sweet side dish, make these Rosemary Roasted Onions. They’re perfectly caramelized and taste great as leftovers.

buttered onion slices in large pot

Recipe Tips for Caramelized Onion Mac and Cheese

  • Salt the pasta water: It’s said your water should “taste like the ocean” for the best tasting pasta.

    Not only does it season the noodles, but it also helps reduce the amount of starch so they don’t stick together.
  • Get perfectly smooth sauce: Adding the half and half slowly while whisking constantly prevents any lumps from forming.

    Allow the dairy to warm on the counter for a bit first to keep it from curdling when it hits the hot pan.
  • Shred the cheese yourself: Because pre-bagged shreds have a preservative to prevent clumping, the cheese often has a waxy texture and doesn’t melt properly.
Dutch oven with caramelized onions

How To Caramelize Onions

Since onions naturally contain a lot of sugar, cooking them for a long period of time releases those sugars and brings out a richer overall flavor.

Just combine sliced or chopped onions with oil or butter, plus some spices if you’d like. Cook over low heat and stir frequently so nothing burns or sticks to the pan.

Also, be sure to leave them uncovered so the liquid that’s released can evaporate. Once they’ve condensed down and turned a deep brown color, they’re done!

Or, make a batch of slow cooker caramelized onions instead.

There is less hands-on work, but you will need to start them early in the morning so they have enough time to cook.

pot of cream sauce for French mac and cheese

Make Ahead Instructions

You can certainly make any baked mac and cheese the day before, then reheat when you’re ready to serve.

Or, simply make the caramelized onions ahead of time and store them in the refrigerator in a sealed container.

Then, proceed with the French onion mac and cheese recipe as directed once you’re ready to cook.

Since the onions are already cooked, you will need to melt additional butter in the pan before making the sauce, about an equal amount to the flour.

mac and cheese in casserole dish topped with caramelized onions

French Mac and Cheese FAQ

Can I save leftover mac and cheese?

Caramelized onion mac and cheese keeps in the refrigerator for 3 to 4 days. Store it in the casserole dish, covered with foil, or transfer it to a separate container with a lid.

For best results, reheat individual portions of French onion mac and cheese in a pan on the stove. Or pop your casserole dish back in the oven until everything is warmed through.

Can I use bread cubes instead?

Yes, but be sure to use unseasoned bread cubes so they don’t affect the overall flavor of the French mac and cheese.

mac and cheese with caramelized onions and bread cubes

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close up: scooping caramelized onion mac and cheese

french onion mac and cheese

French Onion Mac and Cheese + Video

Donna Elick
This creamy baked mac and cheese is bursting with caramelized onion flavor. Make this recipe tonight for the best ever cheesy comfort food!
5 stars from 1 review
Tried this recipe?Please comment and review!
Prep Time 15 minutes
Cook Time 2 hours 20 minutes
Total Time 2 hours 35 minutes
Course Main
Cuisine American
Method Oven
Servings 16


  • 3 cups French Bread, diced
  • 1/4 cup olive oil
  • 16 ounces macaroni noodles
  • 8 tablespoons unsalted butter
  • 4 large sweet onions, sliced thin
  • 4 garlic cloves, sliced thin
  • 8 whole sprigs fresh thyme
  • 1 teaspoon kosher salt
  • 1/2 teaspoon black pepper
  • 1/4 cup all-purpose flour
  • 4 cups half and half
  • 4 cups gruyere cheese, shredded
  • 3 cups white cheddar cheese, shredded
  • 1 tablespoon fresh parsley, chopped fine, optional


  • Preheat the oven to 375°F. 
  • In a large bowl toss the cubed bread with the olive oil. Pour this out onto a baking sheet and toast the bread for 12 minutes, flipping the bread halfway through until lightly golden brown. Set aside. Turn the oven off.
  • In a heavy bottom skillet (or dutch oven) with deep sides over medium-low heat, melt the butter. 
  • Add the onions, garlic, thyme, salt, and pepper, stir to combine. Once the onions are coated in the butter, turn the heat down to low and cook for 2 hours to caramelize the onions, uncovered. Stir frequently to make sure they do not burn. Onions are done when they are cooked down to about a cup and are a very deep brown color.
  • While the onions are browning, cook the pasta per the directions on the back of the box and drain well. 
  • Preheat the oven to 400°F. Spray a 9×13 baking dish with cooking spray, set aside.
  • When the onions are done cooking, discard the thyme sprigs, take out about ¼ cup of the onion mixture, and set aside. Add the flour to the pot and stir to combine in the fat, cook for 2 minutes. Slowly pour in the half & half, whisking constantly. 
  • Bring to a simmer to thicken and take off the heat. Stir in 1 cup of the Gruyere and the 3 cups of white cheddar cheese until melted. Mix the cheese sauce with the macaroni noodles and pour into the baking dish, smooth out the top.
  • Evenly distribute the leftover onions on top of the casserole. Top the casserole with the croutons. Add the remaining 3 cups of the Gruyere on top. 
  • Bake for 15-20 minutes until bubbly and the cheese is browned on top. Be careful not to burn the croutons. Garnish with optional parsley and serve.


Donna’s Notes

Baked mac and cheese will keep in the refrigerator for 3 to 4 days. Store covered or transfer to a separate container with a lid.
For best results, reheat individual portions in a pan on the stove or pop the pan back in the oven until warmed through.


Serving: 1 | Calories: 643cal | Carbohydrates: 56g | Protein: 26g | Fat: 35g | Saturated Fat: 19g | Cholesterol: 94mg | Sodium: 833mg | Sugar: 10g | Fiber: 3g | Calcium: 600mg | Iron: 3mg

All nutritional information is based on third party calculations and is only an estimate. Each recipe’s nutritional value will vary depending on the ingredients used, measuring methods, and portion sizes.

Tried this recipe?Let us know how it was!
titled collage for creamy baked mac and cheese

Originally published November 2020

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  1. Your dish seems great for a family's meeting, easy to prepare so I can do it with my kids. Thanks for sharing!

  2. This recipe sounds delicious,I'm afraid the 13 by 9 inch dish is to small, I will use a slightly larger one, thank you for the recipe

  3. 5 stars
    I was afraid this would be good but man was I wrong! This mac and cheese is so creamy and the onions really stand out! YUM!

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