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If French onion soup and pasta casserole had a baby, this Air Fryer French Onion Casserole would be it. Sweet caramelized onions, rich beef broth, cooking sherry, and fresh thyme come together with tender pasta and melty Gruyère, then finished with a golden, buttery panko crust that the air fryer nails every time. It’s rich, savory, and honestly impossible to stop eating.
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It’s my go-to for weeknight dinners, potlucks, and holiday gatherings because it feeds a crowd beautifully and is the kind of comforting dish that’s always a hit. It’s easy to make ahead and keeps the oven free for everything else on a busy holiday day. Store any leftovers in the fridge for 3 to 4 days.
Ingredients You’ll Need
You’ll need all the ingredients shown in the photograph below.
How to Make Air Fryer French Onion Casserole with Step-By-Step Instructions
Scroll down for the full recipe card containing a full printable recipe and measurements in both US customary and metric units.
Follow these steps and savor this recipe turned ultimate rich, cheesy French onion casserole straight from your air fryer.
Caramelize the Onions
Start by melting butter in a large pot or a large skillet over medium heat. Add onions and cook them slowly, stirring occasionally, until they are thinly sliced, soft, deeply caramelized, and lightly browned, almost like homemade fried onions. The longer they cook, the sweeter and more flavorful they become.
A quality cast-iron skillet like this one makes this step so much easier since the heavy base distributes heat evenly and prevents scorching.
Build the Broth Base
Once the onions are caramelized, stir in the salt and cooking sherry and bring to a gentle boil. Add the flour and cook for 1 to 2 minutes to remove the raw taste, then pour in the beef broth and return to a boil. The sherry adds a subtle depth that gives the soup a restaurant-quality flavor.
Cook the Pasta in the Sauce
Add the uncooked short pasta and cook until al dente, about 10 minutes, or a few extra minutes if needed. Stir in the black pepper, fresh thyme, and half the grated Gruyère (or Swiss cheese for a milder flavor). The pasta absorbs all that savory, onion-rich broth as it cooks, so every piece is seasoned all the way through.
Using a stainless steel box grater to grate your Gruyère fresh makes a noticeable difference in how smoothly it melts.
DO MORE WITH YOUR
AIR FRYER
This eBook is a collection of 86 recipes I make again and again in my own kitchen. If you love good food and easy instructions, this book was made for you.
Immediate eBook download. No physical book available.
Includes ad-free recipes like:
∙ Cheesy Egg Bites
∙ Broccoli Cheddar Soup
∙ Asparagus Casserole
∙ Walking Taco Casserole
∙ Chocolate Cake Cookies
...and much more!
Transfer to a Baking Dish
Spoon the pasta mixture into a baking dish that fits inside your air fryer basket. Spread it out evenly so the top is level and ready for the topping. I love using this silicone spatula to spread the pasta mixture because it makes leveling the top so easy and mess-free.
Add the Cheesy Panko Topping
Mix together the panko breadcrumbs and melted butter, then sprinkle evenly over the top of the casserole along with the remaining Gruyère. A pastry brush helps you coat the panko with butter quickly and evenly, preventing excess grease from pooling and making a mess.
Air Fry Until Golden
Air fry at the highest setting for about 5 minutes, until the cheese is melted and the breadcrumbs are golden and crisp. Watch closely since air fryers vary, and the crust can brown quickly. Finish with fresh thyme and serve warm straight from the dish for a good casserole everyone will love!
Air Fryer French Onion Casserole
Ingredients
- 3 tablespoons butter
- 4 cups yellow onions thinly sliced
- ¾ teaspoon salt
- ¼ cup cooking sherry
- 1 tablespoon fresh thyme chopped (plus extra for garnish)
- 1 tablespoon all-purpose flour
- 3 cups beef broth
- 1 pound short pasta
- ½ teaspoon black pepper
- 1½ cups Gruyère cheese grated
- ½ cup panko breadcrumbs
- 1 tablespoon melted butter
Instructions
- Melt butter in a large pot or Dutch oven over medium heat. Add sliced onions and cook, stirring occasionally, until deeply caramelized.3 tablespoons butter, 4 cups yellow onions
- Stir in salt and sherry, bring to a gentle boil, then add flour and cook for 1–2 minutes. Pour in the beef broth and bring back to a boil.¾ teaspoon salt, ¼ cup cooking sherry, 1 tablespoon all-purpose flour, 3 cups beef broth
- Add uncooked pasta and cook until al dente, about 10 minutes. Stir in black pepper, fresh thyme, and half of the Gruyère cheese.1 tablespoon fresh thyme, 1 pound short pasta, ½ teaspoon black pepper, 1½ cups Gruyère cheese
- Transfer the mixture to a baking dish that fits inside your air fryer basket.
- Combine panko and melted butter, then sprinkle along with the remaining Gruyère over the top.½ cup panko breadcrumbs, 1 tablespoon melted butter
- Air fry at the highest temperature setting for about 5 minutes, or until the cheese is melted and the breadcrumbs are golden.
- Finish with fresh thyme and serve warm.
Notes
- Take your time with the onions: Properly caramelized onions are what give this casserole its deep, rich flavor, so let them cook for 30 to 40 minutes over medium-low heat without rushing.
- Deglaze with the sherry while the pan is hot: Adding the cooking sherry right after caramelizing lifts those flavorful browned bits from the bottom of the pot, deepening the broth with even more rich, layered flavor.
- Use short pasta with ridges: Pasta shapes like rotini, cavatappi, or penne rigate have ridges and curves that grip the savory broth and cheese far better than smooth pasta, so you get more flavor in every bite.
- Grate your Gruyère fresh: Pre-shredded cheese has anti-caking agents that can keep it from melting smoothly, so grating it fresh from the block gives you that silky, perfectly stretchy melt throughout the casserole.
- Match your baking dish to your air fryer basket: Before cooking, make sure your baking dish fits in the air fryer basket with some space around the sides so the topping crisps evenly.
- Flash freeze for easy freezer portions: To freeze leftovers, scoop individual portions onto a parchment-lined baking sheet and freeze for 1 hour, then transfer to freezer bags. This prevents sticking and lets you grab just what you need.
Nutrition
DO MORE WITH YOUR
AIR FRYER
This eBook is a collection of 86 recipes I make again and again in my own kitchen. If you love good food and easy instructions, this book was made for you.
Immediate eBook download. No physical book available.
Includes ad-free recipes like:
∙ Cheesy Egg Bites
∙ Broccoli Cheddar Soup
∙ Asparagus Casserole
∙ Walking Taco Casserole
∙ Chocolate Cake Cookies
...and much more!
How to Store Leftovers
Let the casserole cool to room temperature before storing, then transfer to an airtight glass storage container and refrigerate for up to 3 to 4 days. When reheating, add a small splash of beef broth before microwaving to loosen the pasta and bring back some of that saucy texture.
For longer storage, portion the casserole into individual servings and freeze for up to one month. Thaw overnight in the fridge, then reheat on the stove top, in the microwave, or air fryer to crisp the top again, and the Gruyère will melt beautifully.
What to Serve With Air Fryer French Onion Casserole
A simple green salad with a sharp vinaigrette balances the richness really well, making it a complete meal. Something with a little acidity, like arugula with lemon dressing, or a classic wedge salad, cuts through the savory Gruyère and caramelized onion flavors without competing with them. Crusty bread on the side is always a great call for scooping up any extra saucy pasta from the dish.
If you want to round it out into a bigger spread, adding a few roasted vegetables, like asparagus or French-cut green beans, pairs naturally and keeps things easy. A light fruit salad is also a great addition, especially for holidays and potlucks. It’s rich and filling on its own, so it’s best served with light, fresh sides.
More Easy Recipes for You to Try at Home
If your air fryer gets as much use as mine, you’ll want to try these next.
