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! The sweet onions paired with the soft noodles puts the perfect spin on classic dishes that we all grew up loving and craving!
Mac and cheese was one of my childhood favorites. The buttery flavor paired with the cheese sauce really did create the ultimate comfort food.
But I’m all about creating new recipes out of old classics, and this French onion macaroni really does take the cake.
This is one of those delicious recipes that you’re going to think about for a long time.
The ingredient list is simple as well, making the flavors of this dish stand out even more. When it comes to French onion pasta, you’re going to love this one!
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.
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.
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.
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.
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.
French Mac and Cheese FAQ
Sure. I’m all about adding various cheeses to this dish. Just know that if you do change the cheese, it will change the flavor, but all cheese is good cheese, in my opinion!
Adding Swiss cheese, white cheddar, parmesan cheese, Colby jack cheese, Gruyere cheese, or even a kick of pepperjack cheese all pair well with the cooked pasta.
Just top with a little bit of black pepper and a pinch of salt, and you’ll be set! I also think that adding crispy onions as a topping is yummy, too!
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.
Yes, but be sure to use unseasoned bread cubes so they don’t affect the overall flavor of the French mac and cheese.
With love, from our simple kitchen to yours.
Other Mac and Cheese Recipes
Best French Onion Mac and Cheese Recipe + Video
- 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.
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.
Originally published November 2020, updated and republished February 2024
Disclosure: Posts may contain affiliate links. If you purchase a product through an affiliate link your price will remain the same and The Slow Roasted Italian will automatically receive a small commission. Thank you for supporting us, it helps us keep creating new recipes.