This French Onion Mac and Cheese recipe is a perfect mashup of two comforting classics – mac and cheese and classic french onion soup. So imagine sweet, tender caramelized onions mixed into a gruyere cheese sauce and topped with buttery thyme breadcrumbs.
Ingredients
This recipe combines all the things you love about french onion soup – the caramelized onions - with the best of mac and cheese – a creamy cheesy sauce.
- Pasta: Short pasta shapes work best for mac and cheese, however I don’t love the elbow shape so I did Conchiglie which are kind of a bent rigatoni.
- Onion: Two large yellow onions will get caramelized for the cheese sauce and their natural sweetness will come out and be delicious. Either red onion or vidalia onion won't work as substitutions because they'll change the overall flavor.
- Garlic: A few cloves of garlic add a nice hint of flavor.
- Worcestershire sauce: A depth of flavor that you can’t quite put your finger on but brings umami to the dish.
- Unsalted Butter: The base of the roux.
- All Purpose Flour: Gets mixed with the butter to form the roux.
- Whole milk and heavy cream: These are the base of the cheese sauce.
- Cheddar cheese and gruyere cheese: A combination of sharp cheddar which has so much flavor and gruyere which will bring out the french onion soup flavors. I like white cheddar.
- Panko breadcrumbs: Thick, crispy breadcrumbs serve as the replacement for typical French Onion Soup bread topping in this mac and cheese.
- Melted butter: To help the breadcrumbs get golden brown when baked.
- Thyme: For a fresh herby flavor in the crumb topping.
How to make it
Step by step instructions below for how to make this french onion soup mac, quantities can be found in the recipe card at the end of the post.
1. Warm olive oil over medium low heat in a large oven proof skillet or dutch oven, then add the onions and cook them until caramelized and deep golden brown– about an hour.
2. Add the garlic, worcestershire, a pinch of salt, and cook for 2 minutes until fragrant and then remove to a bowl and set aside.
3. In the pot add the butter, once melted add the flour and cook until dissolved.
4. Add the milk and heavy cream, bring to a simmer and cook until thickened slightly.
5. Take it off the heat and stir in the cheese until melted.
6. Stir in the caramelized onion mixture.
7. Add cooked pasta.
8. In a small bowl combine melted butter, breadcrumbs and thyme.
9. Sprinkle the breadcrumbs over the top of the mac and cheese in an even layer.
10. Bake until bubbly and golden brown on top.
Tips and tricks
- It takes a long time to caramelize the onions – about an hour – don't rush the process!
- To know when your milk and cream mixture is thickened enough, dip a spoon in it then make a stripe with your finger – if the stripe stays then it is thick enough, if the milk dribbles back together, it needs more time.
- If the onions stick to the bottom of the pan add a tablespoon of water or a little bit of white wine and scrape the bottom of the pan with a wood spoon – the fond (stuck on brown bits) will come off and add even more flavor.
- Cook the pasta to al dente because it'll finish cooking as it's being baked in the oven.
- To infuse even more flavor, cook the pasta in beef broth.
- If you don't have an oven safe skillet or dutch oven, transfer the mac and cheese to an oven-safe dish before adding the breadcrumb mixture.
- If you can, shred your own cheese – pre-shredded cheese has other ingredients in it to stop it from clumping, and those ingredients can interfere with a silky cheese sauce. But honestly, at the end of the day it's not a big deal.
Storage and reheating
- Storage: keep in an airtight container in the fridge for up to four days.
- Reheating: warm in the microwave for a few minutes until warmed through.
FAQs
It originated in France in the 18th century.
It is a thickening agent made out of equal parts fat and flour (in this case butter and flour) – it thickens the milk and cream to get a creamy sauce.
Panko breadcrumbs are bigger and more coarse, while regular boxed breadcrumbs are smaller / more fine. So panko breadcrumbs will result in a crispier top.
Nope! In fact it’s better if you don’t, to let the onions get some color and let the natural sugars come out.
Sure! Use a gluten-free pasta and in place of the all purpose flour use an all-purpose GF flour blend or tapioca flour.
Did you make this recipe? Leave a rating and review below and tag me on social!
📖 Recipe
French Onion Mac and Cheese
Ingredients
- 1 lb pasta
- 2 tbsp olive oil
- 2 large yellow onions sliced
- 4 cloves garlic chopped
- 1 teaspoon worcestershire
- ½ teaspoon kosher salt
- 4 tablespoon unsalted butter
- 4 tablespoon all purpose flour
- 3 cups whole milk
- 1 cup heavy cream
- 2.5 cups white cheddar cheese shredded
- 2.5 cups gruyere cheese shredded
- 1 teaspoon kosher salt
Breadcrumb topping
- ½ cup panko breadcrumbs
- 3 tablespoon melted unsalted butter
- 1 teaspoon fresh thyme
Instructions
- Preheat the oven to 425°F.
- Cook your pasta, drain, and set aside.
- In a large oven proof skillet or dutch oven warm olive oil over medium low heat, then add the onions and cook them until caramelized and deep golden brown – about an hour – stirring occasionally.
- To the onions add the garlic, worcestershire, and a pinch of salt. Cook for 2 minutes then remove to a bowl and set aside.
- Add the butter to the same skillet. Once melted add the flour and mix together until dissolved, about 1 minute.
- Add the milk and heavy cream, bring to a simmer over medium heat and cook until thickened slightly, about 5 minutes.
- Take it off the heat and stir in the cheese until melted, followed by the caramelized onions.
- Add the cooked pasta to the cheese sauce and stir to combine.
- In a small bowl combine melted butter, breadcrumbs and thyme.
- Sprinkle the breadcrumbs over the top of the mac and cheese in an even layer.
- Bake until bubbly and golden brown on top, about 15-20 minutes.
PC Lee says
After removing the onions to a bowl once they’re done cooking there’s no mention of what you do with the onions afterwards in terms of incorporating them into the dish. When do you add them ?
Haley says
Sorry about that, it's been updated!
mercy says
If the serving portions are increased to 8 servings, is the cooking time of each step still the same.
Haley says
Generally! I'd just make sure you use a pot large enough. May need a little more time to caramelize the onions.