Homemade Mushroom Green Bean Casserole
A from-scratch upgrade to the classic holiday casserole—no canned soup, just real ingredients and a silky mushroom cream sauce that tastes so much better than anything from a can.
Creator: Leslie Stokes
There’s something about a green bean casserole that just feels like the holidays. It’s one of those dishes that has shown up at every Thanksgiving and Christmas table since the dawn of time… or at least since every mom in the 90s stocked her pantry with cream-of-whatever soups. If you were raised in that era (same), you probably grew up thinking that casseroles must come from a can.
But the truth? Once you make your own “cream of mushroom” from scratch, there’s no going back. It’s richer, silkier, way more flavorful, and honestly just tastes like real food. My kids even said, “Wait… this is green beans?” which, let’s all take a moment because that is a holiday miracle.
This Mushroom Green Bean Casserole is exactly what you want a holiday side dish to be: cozy, creamy, savory, and topped with those crispy fried onions that everyone digs for the second it hits the table. But instead of canned soup, we’re building that creamy base with sautéed mushrooms, onions, garlic, broth, and half & half — plus parmesan if you want to level it up even more. It turns into this beautiful, silky mushroom gravy that coats every single green bean. Truly… chef’s kiss.
And don’t worry, you’re not spending hours on this. The whole thing comes together in under 30 minutes before it even goes into the oven. You blanch the green beans so they stay crisp and bright (nobody wants sad, mushy green beans), then you whisk together the sauce, fold everything into a baking dish, top it with onions, and bake. Easy.
Another perk? You can make this ahead. Because holiday cooking is chaos, and the more you can prep in advance, the better. Just assemble everything without the onions, cover, pop it in the fridge, and bake with the topping when you’re ready.
It’s familiar, but elevated. Nostalgic, but fresh. Classic, but actually tastes homemade instead of “childhood from a can.” And the best part? It always disappears first. Literally always.
If you’ve been looking for the perfect holiday side that your family will request every single year, this is it. And yes — I’m calling it now — you’ll never buy canned cream of mushroom again.
Enjoy, friend. And save me some crispy onions.
Tips for making ahead
1. Blanch your green beans (don’t skip this!)
Boil for 3–4 minutes, then drop straight into ice water.
This keeps them bright, crisp-tender, and prevents a mushy casserole the next day.
2. Make the homemade cream of mushroom up to 3 days ahead
and store it in a jar**
This is the biggest time-saver.
Your sauce will thicken in the fridge, but it loosens perfectly when baked.
3. Assemble everything except the crispy onions
Mix the blanched beans + sauce.
Spread into a casserole dish.
Cover tightly with foil and store in the fridge for up to 48 hours.
Whatever you do—don’t add the onions yet. They get soggy.
4. Bring to room temp before baking
Let the dish sit on the counter for 20–30 minutes before it goes into the oven.
It helps it bake evenly and prevents the sauce from separating.
5. Bake it uncovered so it gets bubbly and reduces
This is what gives you that rich, creamy texture.
No watery casserole here.
6. Add the crispy onions at the very end
Half for baking the last 10 minutes,
half for topping right before serving so you get that perfect crunch.
7. If you want to fully bake it ahead, here’s the trick
Bake it completely without the onions, cool fully, refrigerate.
On Thanksgiving:
•Add a splash of broth or milk
•Reheat at 350°F for 20–25 minutes
•Add crispy onions for the last 5–10 minutes
It tastes fresh—no one will know you made it earlier.
8. Freezer option (shockingly works!)
If you want to prep way ahead:
•Blanch beans
•Make sauce
•Assemble without onions
Freeze for up to 2 months
Thaw overnight, add onions just before baking, and bake as normal.
9. Stir it halfway through baking
This keeps the sauce creamy and evenly coats every bean.
10. Make extra sauce
If you want it extra creamy for the holiday table (you know I do),
double the sauce so you can drizzle a little on top after baking.
Homemade Mushroom Green Bean Casserole
Ingredients
For the casserole:
- 1½ lbs fresh green beans trimmed + halved
- 3 tbsp butter
- 8 oz mushrooms chopped (baby bella or cremini work best)
- ½ yellow onion diced
- 2 –3 cloves garlic minced
- 3 tbsp gluten-free flour or all-purpose
- 1¼ cups chicken broth
- 1 cup half & half or whole milk
- 1 tsp salt
- ½ tsp black pepper
- ½ tsp onion powder
- ½ tsp dried thyme optional but delicious
- ½ cup shredded parmesan optional for extra richness
To top:
- 1½ cups crispy fried onions store-bought or homemade
Let's Make It
- Blanch the green beans: Bring a large pot of salted water to a boil. Add green beans and cook for 5 minutes.
- Drain and rinse with cold water to stop the cooking. This keeps them crisp and bright.
- Make the homemade “cream of mushroom”: In a large skillet: Melt butter → add mushrooms and onions. Sauté until golden, about 6–7 minutes.
- Add garlic and cook 1 more minute.
- Sprinkle the flour over everything and stir to coat.
- Slowly whisk in chicken broth.
- Add half & half.
- Season with salt, pepper, onion powder, and thyme.
- Simmer 4–6 minutes until thickened and creamy.
- Stir in parmesan if using.
- Assemble
- Assemble: Add blanched green beans into the mushroom sauce and toss to coat.
- Transfer everything to a greased 9×13 baking dish.
- Bake: 375°F for 20 minutes until bubbly.
- Top with crispy fried onions.
- Bake for an additional 5-10 minutes until bubbly and golden on top.
