Green Bean Casserole
Ingredients
- 2 lbs fresh green beans trimmed and halved crosswise
- 2 large yellow onions thinly sliced into rings, about 1/8-inch thick
- 1 cup all-purpose flour
- 1 tsp garlic powder
- 1 tsp salt
- 1/2 tsp black pepper
- 2 cups vegetable oil for frying
- 4 tbsp unsalted butter divided
- 1 lb cremini mushrooms cleaned and thinly sliced
- 4 cloves garlic minced
- 1 medium shallot finely diced
- 1 tsp fresh thyme leaves or 1/2 tsp dried thyme
- 3 tbsp all-purpose flour
- 1.5 cups vegetable broth low-sodium
- 1 cup heavy cream
- 1 tsp soy sauce for umami depth
- 1/2 tsp salt or to taste
- 1/4 tsp black pepper
- 3/4 cup Gruyère cheese shredded, divided (optional but highly recommended)
Instructions
- Bring a large pot of heavily salted water to a boil. Add the trimmed green beans and blanch for exactly 4 minutes.
- While beans blanch, prepare a large bowl of ice water. Drain the beans and immediately transfer them to the ice bath to stop cooking. Once cool, drain well and pat dry with paper towels. Set aside.
- In a shallow bowl, whisk together the flour, garlic powder, salt, and pepper. Toss the onion rings in the seasoned flour until well coated, shaking off any excess.
- Heat vegetable oil in a heavy-bottomed skillet or Dutch oven over medium-high heat until it reaches 350°F. Working in small batches, fry the onion rings for 2–3 minutes per batch, stirring gently, until deeply golden and crispy.
- Remove with a slotted spoon and drain on a paper towel-lined wire rack. Season lightly with salt immediately. Set aside. Reserve about 1 cup of the crispiest onions for the topping.
- Preheat your oven to 375°F. Grease a 9x13-inch baking dish and set aside.
- In a large oven-safe skillet or wide saucepan, melt 2 tablespoons of butter over medium-high heat until foaming subsides. Add the sliced mushrooms in a single layer. Cook undisturbed for 3–4 minutes until deeply golden on one side, then stir and cook another 2 minutes. Season with salt and pepper.
- Add the remaining 2 tablespoons of butter, then add the diced shallot and garlic. Cook for 2 minutes until softened and fragrant. Add the fresh thyme.
- Sprinkle the flour over the mushroom mixture and stir constantly for 1–2 minutes to cook out the raw flour taste.
- Gradually pour in the vegetable broth while stirring continuously to prevent lumps. Then pour in the heavy cream and soy sauce. Bring to a gentle simmer, stirring, until the sauce thickens enough to coat the back of a spoon, about 4–5 minutes.
- Remove from heat. Stir in half the shredded Gruyère if using. Taste and adjust seasoning with salt and pepper.
- Add the blanched, dried green beans to the mushroom cream sauce and toss gently until every bean is well coated.
- Transfer the mixture to the prepared baking dish and spread into an even layer. Scatter the remaining Gruyère over the top.
- Bake uncovered at 375°F for 20 minutes, until the sauce is bubbling around the edges.
- Remove from the oven and scatter the reserved crispy fried onions evenly over the top. Return to the oven for an additional 5 minutes until the onions are golden and sizzling.
- For extra crunch, switch the oven to broil for the final 2–3 minutes, watching closely to prevent burning. Let rest 5 minutes before serving.
Notes
Make-ahead: Assemble the casserole without the crispy onion topping, cover, and refrigerate up to 24 hours. Let sit at room temperature 20–30 minutes before baking. Add crispy onions just before the final 5 minutes of baking. Storage: Leftovers keep in an airtight container in the refrigerator for up to 4 days. Reheat in a 350°F oven covered with foil for 15–20 minutes. Add fresh crispy onions when serving to restore crunch. Dairy-free option: Use olive oil instead of butter, full-fat coconut cream instead of heavy cream, and omit or substitute the Gruyère with a dairy-free alternative.