Air Fryer Brussels Sprouts Casserole
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I started making Air Fryer Brussels Sprouts Casserole for holidays, and now everyone asks for it. The sprouts get crispy and caramelized outside while staying tender inside, covered in a creamy sauce that bubbles up golden. The crunchy topping makes every bite even better. It’s the kind of side dish that disappears before the main course even makes it to the table.
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I make this for Thanksgiving, Christmas dinner, and potlucks because it’s a quick side dish that even non–Brussels sprouts lovers will love. It’s crowd-pleasing, make-ahead friendly, and pairs with almost anything. Store leftovers in the fridge for 3 days, then reheat in the air fryer to crisp everything back up.
Ingredients You’ll Need
You’ll need all the ingredients shown in the photograph below.
How to Make Air Fryer Brussels Sprouts 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.
Here’s how to make this crispy Brussels sprouts casserole in your air fryer from start to finish.
Prep the Brussels Sprouts
Trim the Brussels sprouts, removing any tough stems or shriveled and yellowing outer leaves. and cut them in half lengthwise.
Place them in a casserole dish that fits in your air fryer basket, then drizzle with olive oil and season with salt, black pepper, and any spices you like, such as garlic powder, paprika, or onion powder. Toss everything together so each sprout is evenly coated.
I use my favorite 9×13 casserole dish here because it fits perfectly in the air fryer and gives the sprouts enough space to caramelize evenly, making the whole casserole taste richer and more flavorful.
Air Fry Until Caramelized
Set your air fryer to 160ºC (320°F) and cook the Brussels sprouts for 10 minutes, letting the hot air crisp the outside leaves and brown them in spots while the centers soften beautifully. You won’t need to stir them since they sit snugly in the dish.
Make the Creamy Vegan Sauce
While the brussels sprouts cook, grab a small saucepan and melt the vegan butter over medium heat. I like using my nonstick saucepan here because it melts the butter evenly and lets the onions soften without sticking, making the base of the sauce so much richer.
Add the finely chopped onions and garlic powder, then cook for 5-7 minutes until the onions are soft and translucent, then sprinkle in the flour and stir constantly until it forms a thick paste that coats the bottom of the pan.
Pour in the vegetable milk and keep stirring until the sauce thickens and becomes smooth. A silicone spatula like this one lets me stir the mixture smoothly and scrape every bit from the pan without anything sticking.
Assemble and Bake
Remove the casserole dish from the air fryer and pour the creamy sauce over the Brussels sprouts, using a spoon to spread it around so everything gets a nice and even coat. This is where my cooking gloves come in handy, giving me a steady, heatproof grip on the hot dish.
Pop the dish back in the air fryer and cook for another 6 minutes, or until the sauce bubbles up around the edges and the top turns golden.
Add the Toppings
Take the cooked sprouts out and either serve them straight from the casserole dish or transfer them to a large bowl. Sprinkle with chopped parsley and fried onions over the top, adding a little toasted, garlicky breadcrumb if you want extra crunch.
Let the heat bring out an incredible aroma and deepen the flavors, and serve it right away while the sauce is still bubbling and the onions are crunchy. Enjoy!
Equipment
Ingredients
- 4 cups brussels sprouts trimmed and cut in half (fresh)
- 1 tablespoon olive oil
- Salt and pepper
- 1 tablespoon vegan butter
- ¼ cup onions finely chopped
- ¼ teaspoon garlic powder
- 2 tablespoons all-purpose flour
- 1 cup vegetable milk
Toppings:
- Fresh parsley
- Fried onions
Instructions
- Place the brussels sprouts in a casserole dish, season with olive oil, salt and pepper and bake in the air fryer at 160ºC (320°F) for 10 minutes.4 cups brussels sprouts, 1 tablespoon olive oil, Salt and pepper
- In a small saucepan, melt the butter and add the onions and garlic powder. Cook for 5-7 minutes. Add the flour and mix until a thick paste is formed. Add the milk and mix until well combined, stir frequently until it thickens.1 tablespoon vegan butter, ¼ cup onions, ¼ teaspoon garlic powder, 2 tablespoons all-purpose flour, 1 cup vegetable milk
- Remove the brussels sprouts from the air fryer and top with the sauce.
- Bake for 6 more minutes, or until golden brown and bubbly.
- Serve with fresh parsley and fried onions.Fresh parsley, Fried onions
Notes
- Use fresh Brussels sprouts: Fresh ones hold their shape better and get crispier edges than frozen, which tend to release too much moisture in the casserole dish.
- Check your casserole dish size: Make sure your dish fits comfortably in your air fryer basket with at least half an inch of space around it for proper air circulation.
- Don’t skip the flour: The flour is what thickens the sauce and helps it cling to the Brussels sprouts instead of pooling at the bottom of the dish.
- Stir the sauce constantly: Once you add the milk, keep stirring so the sauce doesn’t develop lumps or stick to the bottom of the pan.
- Add fried onions right before serving: If you mix them in too early or store them with the leftovers, they’ll lose their crunch and get soggy.
- Flash cool before storing: Let the casserole cool at room temperature for about 30 minutes before covering and refrigerating so condensation doesn’t make the top soggy.
Nutrition
How to Store Leftovers
Let the casserole cool completely before transferring it to an airtight container with locking lids so the top stays crisp and the sauce doesn’t separate. It can be stored in the fridge for up to 3 days, though the fried onions will soften over time.
To achieve the perfect texture, reheat individual portions in the air fryer at 320°F (160ºC) for 3–4 minutes to crisp everything back up, as the sauce will come back together when warmed even if it separates when cold.
I don’t recommend freezing this casserole since the cream sauce can break when thawed, and the cooked brussels sprouts lose their texture.
If you want to prep ahead, you can roast the Brussels sprouts and make the sauce separately, then store them in separate containers for up to 2 days. Assemble and bake fresh when you’re ready to serve.
What to Serve With Air Fryer Brussels Sprouts Casserole
This casserole pairs beautifully with mashed potatoes, cranberry sauce, or a simple grain like quinoa or rice for a lighter meal. It also works well as part of a Thanksgiving spread or any cozy dinner where you want something creamy and comforting.
For a complete spread, pair it with stuffed acorn squash, garlic roasted potatoes, or a hearty lentil loaf. Round out the plate with a fresh salad or crusty bread to soak up the extra sauce.
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