How This Green Bean Casserole Happened
Funny enough, this from-scratch green bean casserole didn’t start as a holiday recipe at all.
It was spring, months after the holidays, and I randomly found myself craving green bean casserole. I had fresh green beans, baby bella mushrooms, and pretty much everything else I needed—except the can of cream of mushroom soup we usually used.
So I improvised.
I made a creamy mushroom and onion sauce from scratch with baby bella mushrooms, garlic, bone broth, and milk, then made my own crispy Parmesan onions for the top. What started as a use-what-I-have dinner turned into a green bean casserole without canned soup that I liked even better than the version I’d grown up making.
I’ve made it plenty of times since, tweaking it a little each time, and this is the version that finally stuck. Now it’s my perfected homemade green bean casserole—and the one that officially has a spot on our holiday table.
From-Scratch Green Bean Casserole with Crispy Parmesan Onions
Classic green bean casserole, made completely from scratch. Fresh green beans are baked in a creamy mushroom and onion sauce made with bone broth and whole milk—no canned cream-of-anything soup—then topped with homemade crispy Parmesan onions.
Ingredients
Method
Cook the green beans.
- Bring a large pot of water to a boil. Add fresh green beans and cook for 4–5 minutes, until tender but still holding their shape. Drain well and set aside.
- If using frozen green beans, add them directly to the boiling water and cook longer, about 6-8 minutes or until tender. Drain and dry them well before adding them to the casserole so excess water doesn't thin the sauce.
Sauté the mushroom and onion sauce.
- Heat a small amount of avocado oil in a large skillet over medium heat.
- Add the diced onion and sliced baby bella mushrooms. Cook until the onions are soft and translucent and the mushrooms have released their moisture and begun to brown.
- Add the minced garlic and cook for another 30–60 seconds.
Make the roux.
- Add the flour, salt, pepper, garlic powder, onion powder, and dehydrated onion flakes. Stir until the vegetables are evenly coated and cook for 1–2 minutes, stirring frequently.
Make the cream sauce.
- Slowly pour in the chicken bone broth while stirring, followed by the whole milk and Worcestershire sauce.
- Bring to a gentle simmer and cook, stirring frequently, until the sauce has thickened enough to coat the back of a spoon.
- Taste and adjust the seasoning if needed.
Assemble the casserole.
- Fold the cooked green beans into the mushroom sauce until evenly coated.
- Transfer to a casserole dish and spread into an even layer.
Make the crispy Parmesan onions.
- Add the thinly sliced onion and whole milk to a bowl and let the onions soak while you prepare the coating.
- In a separate bowl, combine the flour, Parmesan, salt, pepper, and garlic powder.
- Drain the onions well, then toss with the flour-Parmesan mixture until evenly coated. Drizzle with the avocado oil and toss again.
Air fry the onions.
- Arrange the onions in your air-fryer basket in a relatively thin layer. Air fry until golden brown and crispy, tossing several times during cooking so they brown evenly.
- Oven method: Spread the onions onto a parchment-lined baking sheet and bake at 425°F, tossing occasionally, until golden and crispy.
Bake.
- Bake the casserole uncovered at 375°F for about 20 minutes, or until hot and bubbling around the edges.
- Top generously with the crispy Parmesan onions and return to the oven for another 5 minutes.
- Let the casserole rest for 5–10 minutes before serving.
Notes
No canned soup required. The mushroom sauce is made right in the pan with butter, onions, mushrooms, bone broth, and whole milk. I use homemade chicken bone broth because I almost always have some in my freezer, but store-bought chicken broth or vegetable broth works perfectly well.
Fresh or frozen green beans: I prefer fresh, but frozen absolutely works. Thaw frozen green beans in hot water first, then drain and dry them really well. Extra water can thin out the sauce.
Don’t skip the Worcestershire. It’s a small amount, but it adds that deep savory flavor that makes the mushroom sauce taste like it’s been cooking much longer than it has.
Air fryer vs. oven: I usually make the Parmesan onions in my air fryer because it’s quicker and gets them really crispy, but I’ve made them in the oven plenty of times and they’re just as good.
Make ahead: Prepare the green beans and mushroom sauce and assemble the casserole ahead of time, but keep the crispy onions separate. Refrigerate the casserole, then add the onions toward the end of baking so they stay crispy.
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