Ultimate Green Bean Casserole
Elevate your holiday table with this gourmet green bean casserole featuring a rich brown butter and Parmesan béchamel, fresh crimini mushrooms, and a classic crispy onion topping.
Equipment
- Large Pot
- Large Skillet
- Large saucepan
- 2-qt casserole dish
Ingredients
- 2 lb. fresh green beans
- Kosher salt
- 2 Tbsp. extra-virgin olive oil, divided
- 1 lb. crimini mushrooms, sliced, divided
- 6 Tbsp. unsalted butter, divided
- 4 large sprigs thyme, divided
- 2 Tbsp. all-purpose flour
- 1 1/4 cups whole milk
- 1 cup heavy cream
- 4 cloves garlic, finely grated
- 1/2 cup grated Parmesan
- Freshly ground black pepper
- 3/4 cup French’s fried onions
Instructions
Prep the Beans and Oven
- Set a rack in the middle of the oven and preheat to 375°F. Bring a large pot of heavily salted water to a boil, then cook the fresh green beans in batches for about 3 minutes per batch, just until bright green and halfway tender.
- Drain the beans and cool them quickly in an ice bath to stop the cooking. Once cooled, trim the stem ends to ensure the beans do not soak up excess water.
Brown the Mushrooms
- Heat 1 Tbsp olive oil in a large skillet over medium-high heat. Add half of the sliced mushrooms in a single layer and sear for 2 minutes without stirring. Toss and cook 3 minutes more until browned.
- Add 2 Tbsp butter and 2 thyme sprigs to the skillet. Cook for 4 minutes longer until the butter is nutty and mushrooms are dark brown. Season with salt and transfer to a plate. Repeat this entire process with the remaining oil, mushrooms, 2 Tbsp butter, and remaining thyme.
Build the Sauce
- Melt the remaining 2 Tbsp butter in a large saucepan over medium-low heat. Whisk in the flour and cook for 4 minutes until the roux turns golden and toasted.
- Slowly stream in the milk and heavy cream while whisking. Bring to a simmer over medium heat and cook for 5 minutes, whisking often, until the béchamel is thick enough to coat a spoon.
- Remove from heat and whisk in the grated garlic and Parmesan. Season with salt and black pepper to taste.
Assemble and Bake
- Arrange the blanched green beans and browned mushrooms in a 2-qt casserole dish. Pour the cheese sauce evenly over the top.
- Cover the dish tightly with foil and bake for 25 to 30 minutes, until the sauce is bubbling.
- Remove the foil and bake for another 15 to 20 minutes until the edges are golden. Scatter the fried onions over the top and bake for 3 minutes until fragrant. Let rest for 10 minutes before serving.
Notes
Ingredient Selection: Fresh green beans are essential for the best texture. Avoid canned beans as they will become too soft and make the sauce watery.
Mushroom Tip: Do not crowd the skillet when browning mushrooms. Cooking them in batches allows them to caramelize and develop deep umami flavor rather than steaming.
Make-Ahead Instructions: You can blanch the beans and prepare the sauce up to 24 hours in advance. Store them separately in the fridge and assemble just before you are ready to bake.
Reheating: To preserve the crunch of the onion topping, reheat leftovers in a 350°F oven for 10 to 15 minutes or in an air fryer for 3 to 5 minutes.
Nutrition information is estimated based on common ingredients and serving sizes and may vary.
Nutrition
Calories: 345kcalCarbohydrates: 18gProtein: 9gFat: 28gSaturated Fat: 16gCholesterol: 75mgSodium: 420mgPotassium: 480mgFiber: 5gSugar: 6gVitamin A: 1150IUVitamin C: 14mgCalcium: 180mgIron: 2mg
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