This caramelized onion green bean casserole features a creamy, cheesy green bean filling with lots of flavorful caramelized onions and crispy breadcrumbs on top.
We’re definitely messing with a classic Thanksgiving side dish today, but trust me you’ll be very glad we did.
Turns out that caramelized onions, crispy breadcrumbs, and lots of cheese is just the twist that green bean casserole needed.
Are you ready for a humble lil green bean casserole to be the star of your holiday table? Keep reading.
This Caramelized Onion Green Bean Casserole features…
- Tender steamed green beans.
- A perfectly creamy béchamel sauce.
- Layers of gooey cheddar, caramelized onions, and crispy panko breadcrumbs.
Making the Caramelized Onion Green Bean Casserole
(scroll down to the bottom of the post for the full recipe)
Ingredients You Will Need
- Green beans
- Vidalia onion
- Unsalted butter
- Olive oil
- All-purpose flour
- Heavy whipping cream
- Vegetable broth (or chicken broth)
- Cheddar cheese
- Panko breadcrumbs
How to Caramelize Onions
You will need 1 large sweet Vidalia onion to make the caramelized onions for this recipe. Slice the onion into thin strips and it’s ready for cooking!
The trick with caramelizing is cooking the onions very slowly. You’re going to want to cook the onion in a little butter + olive oil over medium heat for about 20 minutes. Stir the onions occasionally until they are a deep caramelized brown.
That’s all there is to caramelized onions! You can easily make them ahead of time and store in the fridge for recipes.
Tips for Perfect Green Bean Casserole
- Steam green beans to crisp-tender – it’s super important to not cook the green beans entirely while steaming because they will continue cooking in the casserole.
- Shock green beans in ice water – this will stop the cooking process so that the beans don’t end up overcooked.
- Saute mushrooms with caramelized onions – once the caramelized onions are done, add the mushrooms and give them a quick saute until tender.
- Layer cheese, onions, and breadcrumbs on top – start with a layer of cheese then top with caramelized onions and panko.
- Allow casserole to stand before serving – once the casserole is baked, allow to stand several minutes before serving to allow it to set a bit.
You can assemble this casserole entirely ahead of time! Follow these make ahead instructions…
- Caramelize onions – onions may be caramelized and stored in the fridge up to 6 days.
- Steam green beans – steamed green beans may be stored in the fridge up to 3 days.
- Assemble casserole – prep the entire casserole and store in the fridge up to 3 days. When ready to bake, add an additional 5 minutes to bake time if baking from cold.
Try these ideas for a different twist on this recipe!
- Skip the mushrooms – not a fan of mushrooms? You can easily leave them out of this recipe.
- Add more veggies – sauteed sweet pepper or zucchini would be great veggie additions.
- Change up the cheese – try Parmesan, asiago, gouda, or colby jack in place of the cheddar.
- Add meat – crumbled bacon or cooked chicken/turkey would be great meaty additions.
You just can’t beat the amount of flavor we’re piling into this killer green bean casserole! The combination of the flavorful caramelized onions paired with the tender green beans and creamy, cheesy sauce is just the best thing ever.
Ready for a green bean casserole to steal your holiday spotlight? It’s guaranteed to happen.
Save this recipe using the ‘save to recipe box’ button below. If you make it, please let us know! Leave a comment + star rating below, or take a photo and tag it on Instagram with #wholeandheavenlyoven.
More delicious casseroles to try next!
- Skillet Green Chile Chicken Enchilada Casserole
- Cheesy Zucchini Rice Casserole
- Baked Penne Alla Vodka
Caramelized Onion Green Bean Casserole
- 1 tablespoon olive oil
- 1/2 tablespoon, plus 2 tablespoons unsalted butter, divided
- 1 large Vidalia sweet onion, thinly sliced
- 1 cup button mushrooms, chopped into 1/2-in pieces
- 1-1/2 lbs fresh green beans, ends trimmed and beans cut into 1-in pieces
- 2 medium cloves garlic, minced
- 2 tablespoons all-purpose flour
- 3/4 cup 2% or skim milk
- 1/4 cup heavy whipping cream
- 1/2 cup vegetable broth (or chicken broth)
- 1 cup shredded mild cheddar cheese
- 1/2 cup panko bread crumbs
- In a large skillet over medium heat, melt olive oil and 1/2 tablespoon butter, swirling pan to evenly coat. Add onions and cook over medium heat, stirring occasionally until onions are a deep golden brown, about 20 minutes.
- Add mushrooms to pan and saute an additional 3-4 minutes or until mushrooms are softened. Transfer to a bowl and set aside.
- Preheat oven to 400F. Place green beans in a steamer basket set over a pot of boiling water. Allow to steam 3-5 minutes until crisp-tender. Immediately plunge green beans into ice water to stop the cooking process and drain well.
- In a large high-walled skillet, melt remaining 2 tablespoons butter over medium heat. Add garlic and saute 1 minute until fragrant. Whisk in flour and cook several minutes until golden brown. Slowly begin whisking in milk, heavy cream, and vegetable broth, mixing constantly until smooth.
- Bring sauce to a simmer over medium heat, stirring occasionally until sauce is slightly thickened and bubbly. Fold in green beans and half of caramelized onions/mushrooms until evenly coated.
- Scrape green bean mixture into a greased 9×13 pan or 9-inch skillet. Top with cheddar, remaining caramelized onion/mushroom mixture, and breadcrumbs.
- Bake green bean casserole at 400F 25-30 minutes until top is golden-brown and casserole is bubbly. Allow to cool several minutes before serving warm. Enjoy!