Creamy, cheesy, and popping with flavor, do your green beans differently and try Green Beans Au Gratin. Perfect for Thanksgiving or Christmas or any time you want to jazz up your green beans side dish, this is a fabulous and delicious recipe!

fresh Green Beans Au Gratin

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Vegetables don’t have to be boring! When you’re in the mood for a deliciously different way to do green beans, check out this Green Beans Au Gratin recipe. It’s saucy, flavorful, savory, and the crunchy topping pairs so well with the tender green beans.

Green Beans Au Gratin

This is such a pretty dish, too. It’s a great substitute for green bean casserole, and the cheesy sauce envelops all the beans creating a dish that pairs perfectly with roasted turkey and all your other holiday side dishes.

green bean onion bite

I love this green bean recipe around the holidays, but it’s fancy enough for any special meal. And like many of my favorite dishes, you can prep most of this one ahead of time to limit your time in the kitchen if you’re entertaining friends and family.

baked Green Beans Au Gratin

Why I love this recipe

  • It’s creamy, savory, and saucy, and the crumbed topping is amazing!
  • You can prep it ahead of time – see my tips below!
  • Roasting the green beans first brings out all their sweet flavor!

ingredients green beans gratin

Gather these ingredients

  • Green beans – Trimmed and cut into 1 to 2-inch pieces.
  • Extra-Virgin olive oil
  • Onion – Yellow or white onion is fine.
  • Leeks – Thinly sliced and washed.
  • Mushrooms – Thinly sliced.
  • All-purpose flour – You can use almond flour
  • Salt and white or black pepper
  • Milk – Low-fat milk or whatever you have on hand.
  • Gruyere cheese – Shredded.
  • Fresh herbs – Thyme, sage, or parsley or a combination.
  • Fresh breadcrumbs – See my notes below on how to make fresh breadcrumbs.
  • Almonds – Thinly sliced and toasted.

how to make gratin

How To Make Green Beans Au Gratin

  1. Preheat your oven to 425-F.
  2. Toss the cut green beans with 1 tablespoon of oil and roast the green beans in an even layer until they start to brown. Use 2 baking sheets if the green beans aren’t in a single layer.
  3. Heat 1 tablespoon of oil in a saucepan and add the thinly sliced onion and saute until golden brown.
  4. Add 1 tablespoon of olive oil and add the leeks and mushrooms and cook until tender.
  5. Add the flour, salt and pepper and cook for a minute, then whisk in the milk and cook over low heat until it thickens and boils.
  6. Add ½ cup of the shredded cheese until it melts and turn off the heat.
  7. Spray a 9×13 baking dish with cooking spray and layer half the green beans into the baking dish.
  8. Top the layer of green beans with half the sauce, repeating with another layer of green beans and sauce.
  9. Combine the breadcrumbs, the toasted almonds, the remaining tablespoon of oil, and ½ cup of the shredded cheese in a small bowl and sprinkle this over the top of the gratin.
  10. Place the baking dish under the broiler and broil until bubbling and brown. Let stand for 10 minutes before serving and enjoy!

how to assemble Green Beans Au Gratin

Tips & substitutions

  • To make this dish ahead of time, you can roast the green beans up to 30 minutes ahead of time, and the sauce can be made a day ahead and refrigerated until ready. Heat the sauce before combining it with the green beans.
  • To make fresh breadcrumbs: trim crusts from whole-wheat bread and pulse the bread in a food processor until they are coarse crumbs. One slice of bread makes about ½ cup of fresh breadcrumbs.
  • Stir fresh herbs into the sauce to make it extra flavorful.
  • Switch up the cheese or add more cheese. Swiss, cheddar, and blue cheese are all great options.
  • Watch the dish while it’s under the broiler, so it doesn’t burn! 

Green Beans Au Gratin with breadcrumbs

Serving suggestions

For the holidays, I love these Green Beans au Gratin with other sides like Carrot Souffle, Apple-Cranberry Chutney, and Baked Sweet Potatoes. This dish goes amazingly well with roasted turkey, ham, chicken, beef, and even pork

Green Beans Au Gratin recipe


Store any leftover Green Beans au Gratin in the fridge for 2-3 days. It’s best to keep them in an airtight container or in a container covered tightly with foil. Foil is best at creating a barrier that doesn’t let unwanted flavors in (or out) while you store your food.

fork bite of gratin

Check out these awesome green bean recipes while you’re here

fresh Green Beans Au Gratin
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Green Bean Au Gratin

Yield: 8
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  • 2 ½ pounds green beans, trimmed and cut into 1- to 2-inch pieces (about 8 cups)
  • 3-4 tablespoons extra-virgin olive oil, divided
  • 1 medium onion, thinly sliced
  • 1 cup thinly sliced winter leeks
  • 1 cup thinly sliced mushrooms, we like baby portabellas
  • 3 tablespoons all-purpose flour
  • ¾ teaspoon salt
  • ¼ teaspoon white or black pepper
  • 2 ½ cups low-fat milk
  • ¾ cup shredded Gruyère cheese, divided
  • 1 tablespoon chopped fresh herbs, such as thyme, sage or parsley
  • 1 ½ cups fresh whole-wheat breadcrumbs, or you can use gluten-free
  • ½ cup thinly sliced almonds, toasted


To roast the green beans:

  • Preheat oven to 425 degrees F. Prepare a 9x13 baking dish with cooking spray (or butter).
  • Toss green beans in a large bowl with 1 tablespoon oil until well coated. On a large baking sheet (or 2 baking sheets) spread in an even layer. Roast, stirring once until tender and beginning to brown, 20 to 25 minutes. If using 2 pans, rotate the pans top to bottom about halfway through.
  • Meanwhile, heat 1 tablespoon oil in a large saucepan over medium heat. Add onion and cook, stirring frequently, until very soft and golden brown, 2-4 minutes. Add another tablespoon of oil and the leeks and mushrooms and cook for another 6-8 minutes.
  • To the onion mushroom mixture, add flour, salt and pepper; cook, stirring, for 1 minute more. Pour in milk and continue to stir, scraping up any browned bits. Cook, stirring, until the sauce bubbles and thickens enough to coat the back of a spoon, about 4 minutes. Add in the 1/2 cup of cheese until it melts.
  • When the green beans are done, remove from the oven. Preheat the broiler.
  • Transfer half the green beans to a 9x13 baking dish. Spread half the sauce over the green beans. Add the remaining green beans and top with the remaining sauce.

To make the breadcrumbs:

  • Combine breadcrumbs, the remaining 1 tablespoon oil, and 1/4 cup shredded cheese in a small bowl.
  • Sprinkle the breadcrumb mixture over the gratin. Place under the broiler and broil, watching closely, until the gratin is bubbling and beginning to brown on top, 1 to 5 minutes, depending on your broiler. Let stand for 10 minutes before serving.
Cuisine: American
Course: Side Dish
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Green Beans Au Gratin with fresh breadcrumbs