French Onion Green Bean Casserole is a delicious and elevated side dish using fresh ingredients! Add it to your favorite holiday dishes for a nice little twist on the classic green bean casserole.

Creamy French Onion Green Bean Casserole

Love it or hate it, the traditional green bean casserole has been a staple of Thanksgiving tables in the US since the 1960s. You know the version…green beans, canned soup, milk, soy sauce and of course, crispy onions on top. I’ve enjoyed it plenty in my time, but this year, I want something a little different.

French onion inspiration is popping up everywhere! So, it should be no surprise that its made its way to into a classic green bean casserole. We’re borrowing the best parts of French onion soup for this version: caramelized onions + melty gruyere cheese! Add some half & half for a velvety textured sauce and top it all with a layer of crispy breadcrumbs and you’ve got the perfect side dish for thanksgiving dinner or any night of the week.

A breadcrumb topped green bean casserole in a white dish.

Gather Your Ingredients

In addition the kosher salt and fresh cracked black pepper, you’ll need:

Fresh green beans – or frozen green beans. When buying fresh beans, look for firm, bright green, blemish free beans. You’ll trim the stems off and cut them into smaller bite size pieces. When buying frozen, look for ‘cut’ green beans to save you the step of trimming and cutting.
Sweet onions – any of the sweet varieties are perfect, such as Maui and Vidalia.
Unsalted butter – is there anything better than the smell of onions sautéing in butter?!
Dry sherry – a fortified wine that will lend its nutty, tangy flavor to the casserole.
White sugar – to help the onions’ caramelization process along.
Fresh garlic – for another layer of flavor.
All purpose flour – to help thicken the sauce
Vegetable broth – you can also use chicken broth. I like low-sodium varieties for more control over the seasoning.
Half & half – for a silky texture and to give the sauce a little more richness.
Gruyere cheese – the classic melting cheese used in French onion soup.
Panko breadcrumbs – this replaces the crouton from French onion soup and adds another texture and a light crispiness.
Garlic powder – to add some extra flavor to the crumb topping.

Raw ingredients on a white marble table for green bean casserole.

How to Make French Onion Green Bean Casserole

Blanche the green beans – boil the green beans in a large pot of water for 3 minutes. Drain and rinse under cold water to stop the cooking. Set aside. (Or, plunge the cooked beans into an ice bath.)
Sauté the aromatics – return the empty green bean pot to medium heat and melt 4 tablespoons of butter. (You can also use a large skillet if you prefer.) Add the onions and sugar and cook for 20 to 25 minutes until the onions are soft and golden. Add garlic and cook for another minute to release their fragrance. Finally, add the sherry and allow it to boil off.
Make the creamy sauce – stir flour into the onions and cook for 3-4 minutes. Stir in the broth and half & half and bring to a bubble. Continue cooking for 2-3 minutes until the sauce begins to thicken. Season with kosher salt & fresh cracked black pepper.
Coat the green beans – return the green beans to the pot and toss to coat evenly. Transfer the green bean mixture to a prepared casserole dish, then sprinkle shredded gruyere over the top.
Top with breadcrumbs + bake – toss panko and garlic powder with melted butter, then sprinkle it over the casserole. Bake uncovered for 30-35 minutes at 350°F until the top is golden brown.

A spoon scooping out a serving for french onion green bean casserole.

How to Slice the Onions

It’s typical to cut an onion in half and then slice half moons across the grain. However, that tends to lead to long stringy strands of onion. There’s nothing wrong with that, but for this recipe, it’s nice to have pieces that resemble little shards, or julienned strips, of onion that resemble the green beans in shape and size.

Instead of slicing the onion across the grain, cut the stem end away as well and make slices with the grain, from stem to top.

Julienned onions on a yellow cutting board.

Make Ahead Instructions

This is a great make-ahead dish for your holiday meal. Assemble the entire casserole except for the breadcrumb topping. Cover the baking dish tightly with plastic wrap and refrigerate. Allow it to rest at room temperature while the oven preheats. Make and sprinkle it with the breadcrumb topping just before baking.

Substitutions + Additions

Add some extra flair to your French onion green bean casserole!

Mushrooms – just because I’ve omitted the canned cream of mushroom soup, doesn’t mean you have to do without mushrooms. Sauté 8 ounces of your favorite fresh mushrooms and add them to the sauce to create a creamy mushroom sauce.
Nutmeg – add a couple pinches of nutmeg to the sauce to give it a warm vibe.
Herbs – include fresh herbs like thyme or parsley.
Cheese – add some grated parmesan to the breadcrumbs; swap out the gruyere for white cheddar cheese.
Onions – without the caramelized onions, this would just be a green bean casserole…that’s a different recipe. However, if you simply can’t live without your crispy fried onions, by all means add them to the top of your casserole!

A serving spoon resting in a casserole dish filled with green beans.

Storing + Reheating Leftovers

Transfer leftover green bean casserole to an airtight container and refrigerate for 2 to 3 days. Reheat leftovers in a 350°F oven until hot throughout and the topping has re-crisped.

Check Out More Side Dishes!

French Onion Green Bean Casserole

Linda Feller

French Onion Green Bean Casserole is a delicious and elevated side dish using fresh ingredients! Add it to your favorite holiday dishes for nice little twist on the classic green bean casserole.

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1 5

1 40

Side Dish

American, French

256 kcal

Equipment

Ingredients

24 ounce green beans, fresh or frozen, trimmed + cut in half
6 tablespoon unsalted butter, divided
2 medium sweet onions, about 1-1/2 lbs, halved + sliced thin from root to tip
1 teaspoon white sugar
2 cloves garlic, minced
2 tablespoon dry sherry
2 tablespoon all purpose flour
1 cup low-sodium vegetable broth
¾ cups half & half
kosher salt + fresh cracked black pepper
1 cup shredded gruyere cheese
½ cup panko breadcrumbs
½ teaspoon garlic powder

Instructions

Bring a large pot of salted water to a boil over high heat. Boil the green beans for 3 minutes. Drain in a colander and immediately run cold water over the beans to stop the cooking. Drain well and set aside.
Preheat oven to 350°F. Spray a 2-quart casserole with cooking spray.
Return the pot to a burner over medium heat. Add 4 tbsp of butter to melt. Add the onions and sugar; toss together. Cook the onions for 20 to 25 minutes until they are soft and golden brown. Stir every so often to prevent burning; adjust the burner down a little if they are getting color too quickly. Add the garlic during the last couple minutes to release their fragrance. Finally, add the dry sherry and allow it to cook off.
Stir the flour into the onions and cook for another 3 to 4 minutes. Continue stirring to prevent sticking.
Stir in the broth and half & half. Bring it to a bubble; cook for 2 to 3 minutes until it begins to thicken. Take it off the burner. Season with kosher salt + fresh cracked black pepper.
Return the green beans to the pot and toss to coat in the sauce. Transfer the green bean + onion mixture to the prepared casserole. Sprinkle shredded gruyere over the top.
Melt the remaining 2 tbsp of butter and combine it with the Panko and garlic powder in a small bowl. Sprinkle over the top of the casserole.
Bake uncovered for 30-35 minutes until the topping is golden brown.

Notes

To Thoroughly Drain Green Beans: Place a tea towel over a sheet pan. Spread the green beans out in an even layer to dry while the onions caramelize.
Make-Ahead Instructions: Assemble the entire casserole except for the breadcrumb topping. Cover the baking dish tightly with plastic wrap and refrigerate. Allow it to rest at room temperature while the oven preheats. Make and sprinkle it with the breadcrumb topping just before baking.
Storing & Reheating Leftovers: Transfer leftover green bean casserole to an airtight container and refrigerate for 2 to 3 days. Reheat leftovers in a 350°F oven until hot throughout and the topping has re-crisped.