These Green Beans with Mushroom Sauce are a deconstructed take on green bean casserole, perfect for a holiday dinner. Instead of baking everything together, the beans roast on their own until crisp-tender, then get topped with a rich mushroom cream sauce and buttery Parmesan breadcrumbs before heading to the table.
Before You Start Cooking
- Mushrooms: Cremini mushrooms (“baby bellas”) bring a deeper flavor to the sauce than white button mushrooms. Dice them into small pieces so the sauce drapes over the green beans.
- Green beans: Look for fresh, firm beans that snap when you bend them. Try to pick ones that are similar in thickness so they roast evenly and finish at the same time.
- Sherry: Use a dry sherry from the liquor store. I often use Taylor for cooking. Skip the “cooking sherry” in the grocery store vinegar aisle. It’s loaded with salt, which concentrates as it cooks down.
- Topping: I love the buttery Parmesan-thyme panko here, but if you want to lean into the classic green bean casserole vibe, try crispy frizzled shallots or French-fried onions instead. Sprinkle them on right before serving, just like the breadcrumbs.
How to Make Green Beans with Creamy Mushroom Sauce
Step 1: Roast the Green Beans
Heat the oven to 425°F and line a rimmed half sheet pan with foil or parchment. While it heats, wash the green beans, dry them well, and trim off the stem ends. No need to remove the skinny tail ends.
Toss the beans with olive oil, salt, and pepper. Use regular olive oil for roasting (not extra virgin), or a high-heat one like Graza Frizzle. Then spread the beans out in a single layer on the pan.
Roasting time will depend on how thick the beans are. Standard green beans take about 15 to 20 minutes (flip them halfway through with tongs or a spatula). Thinner haricots verts (French green beans) are usually ready in 12 to 15 minutes.
Pull them when you see blistered, browned spots and the beans are tender but still have a little bite. They’ll soften a bit more under the warm sauce.
If your family likes softer green beans (like mine does), add about 5 minutes to the roasting time.
Step 2: Toast the Parmesan-Thyme Breadcrumbs
While the beans are in the oven, melt a pat of unsalted butter in a small skillet over medium heat. Add plain panko breadcrumbs and cook for 2 to 3 minutes, until they’re toasty and golden.
Don’t walk away from the stove for this part. Keep stirring so the crumbs toast evenly, because panko can go from perfectly toasted to burnt pretty quickly.
Once they’re golden, pour them out of the skillet and into a bowl right away. If they sit in the hot pan, they’ll keep toasting.
Stir chopped fresh thyme and a pinch of salt into the warm crumbs, then let them cool for about 10 minutes. Then, stir in finely grated Parmigiano Reggiano.
If you add the cheese too soon, it will melt and clump in the hot breadcrumbs. Waiting keeps the topping light and crispy, ready to sprinkle over the platter.
Step 3: Make the Creamy Mushroom Sauce
Now for the mushroom sauce, which is honestly my favorite part of this dish!
Brown the Mushrooms
Melt a little more butter with a splash of olive oil in a medium skillet over medium-high heat. Add the chopped yellow onion and let it cook for a few minutes, until it starts to soften.
Next, stir in the mushrooms. They’ll release a good amount of liquid at first. Keep cooking until the liquid evaporates and the mushrooms are nicely browned. This will take about 6 to 8 minutes.
This is where the sauce gets its depth, so don’t rush it. Give them a stir every so often, but not constantly, so they make good contact with the hot pan and brown instead of steaming.
Once they’re browned, add the minced garlic and fresh thyme and cook for about 30 seconds, until the garlic is fragrant.
Then deglaze the pan by pouring in the dry sherry and scraping up all those browned bits on the bottom of the pan with a wooden spoon. The fond on the bottom of the pan is flavor you don’t want to leave behind!
In just about a minute, the sherry will cook off completely. The sauce won’t taste boozy; the sherry just adds a subtle, nutty, savory depth and enough brightness to balance the richness of the cream and Parmigiano Reggiano.
Build the Sauce
Stir all-purpose flour into the mushrooms and cook for about a minute to prevent a raw flour taste in the finished sauce.
Now add chicken or vegetable stock gradually, stirring the whole time so the flour dissolves without lumps. I like a moderate-sodium chicken stock, such as Swanson or Kirkland, so I can control the salt in the finished sauce.
Stir in the heavy cream, Dijon mustard, and black pepper. Once the sauce starts to bubble, turn the heat down and let it simmer for 5 to 6 minutes, stirring occasionally, until the sauce coats the back of a spoon.
To finish the sauce, stir in finely grated Parmigiano Reggiano, gently simmering until it melts and the sauce thickens slightly.
Since the stock and cheese add varying amounts of saltiness, taste the sauce and add salt only if needed. I usually add between ¼ and ½ teaspoon of kosher salt.
When finished, the sauce should be thick but still pourable. If it thickens too much, an extra splash of stock will loosen it back up.
Step 4: Assemble and Serve
Right before you’re ready to serve, pile the roasted green beans onto a large platter and spoon the mushroom sauce over the top. Unlike green bean casserole, you don’t need to fully coat every bean.
If you’re using a smaller platter and the beans are piled high, layer them with the sauce as you go so the beans on the bottom don’t end up naked.
Finish with a generous sprinkle of the Parmesan-thyme breadcrumbs and serve right away, while the topping is still crunchy.
Serving Green Beans with Mushroom Sauce
For Thanksgiving: These green beans go with everything else on the table, from turkey and mashed potatoes to stuffing. They need a 425°F oven, so the easiest time to roast them is while the turkey rests.
Beyond Turkey Day: Roasted Green Beans with Mushroom Sauce are just as good next to a Christmas roast or Easter ham. For a regular weeknight or Sunday dinner, serve them with roasted chicken, pork tenderloin, or steak.
Keep the sauce warm: Running behind? Hold the sauce in a makeshift bain-marie, a heatproof bowl set over a pot of barely simmering water. It stays warm and pourable without scorching on the bottom of the pan. If the sauce thickens while it waits, stir in a splash of stock before serving.
Make Ahead and Storage Tips
Prep Ahead
On a busy holiday, it helps to get some of the prep done early. You can make the mushroom sauce up to 2 days ahead and keep it in an airtight container in the fridge.
You can also toast the breadcrumbs a couple of days early. Just make sure they’re completely cool before putting them in an airtight container. If they’re still warm, they’ll steam and lose their crunch.
Keep them on the counter and save the Parmigiano for serving day. Stir it into the crumbs right before they go on the platter.
When you’re ready to serve, warm the sauce gently over low heat, adding a splash of stock to bring it back to a pourable consistency. Then, your only last-minute jobs are roasting the beans, drizzling the sauce, and sprinkling on the topping.
Leftovers
Refrigerate leftovers in an airtight container for up to 3 days. The breadcrumbs will soften as they soak up the sauce, and there’s no way around that once the dish is assembled. If you’re expecting leftovers, I recommend making extra crumbs to keep on hand.
Before reheating, scrape off as much of the softened panko as you can. Add a small splash of stock to help steam the beans and loosen the sauce.
Then warm everything in a skillet over medium-low heat, or in a loosely covered baking dish at 350°F for 15 to 20 minutes, stirring halfway through.
Top with fresh crumbs right before serving.
More Holiday Side Dishes
Craving more? Check out this collection of my favorite Thanksgiving sides.
Green Beans with Mushroom Sauce
Ingredients
Roasted Green Beans
- 1½ pounds fresh green beans , stem ends trimmed
- 1½ tablespoons olive oil (regular or high heat, not extra virgin)
- ½ teaspoon Diamond Crystal kosher salt
- ¼ teaspoon freshly ground black pepper
Parmesan-Thyme Breadcrumbs
- 1 tablespoon unsalted butter
- ½ cup plain panko breadcrumbs
- ½ teaspoon chopped fresh thyme leaves
- ¼ cup finely grated Parmigiano Reggiano
- pinch kosher or sea salt
Mushroom Cream Sauce
- 1 tablespoon unsalted butter
- 1½ teaspoons olive oil
- ½ cup finely diced yellow onion (about ½ medium onion)
- 1¼ cups small diced cremini mushrooms (3-4 "Baby Bella" mushrooms, stems removed)
- 2 large garlic cloves , minced
- 1 teaspoon chopped fresh thyme leaves
- 2 tablespoons dry sherry (not cooking sherry, see Note)
- 1 tablespoon all-purpose flour
- 1 cup chicken or vegetable broth or stock (see Note 1)
- ¾ cup heavy cream
- 1 teaspoon Dijon mustard (I use Maille)
- ¼ cup finely grated Parmigiano Reggiano
- kosher salt and freshly ground black pepper
Instructions
Roast the Green Beans
- Preheat oven to 425℉ with the rack in the middle position. Line a rimmed half sheet pan with foil for easy cleanup.
- Toss together the green beans, olive oil, salt and pepper. Spread into a single layer on the prepared baking sheet. Roast for 15 to 20 minutes, flipping halfway through, until blistered and browned in spots but still tender-crisp (see Note 2). For softer beans, roast 5 minutes longer.
Make the Breadcrumb Topping
- While the green beans are roasting, melt the butter in a small skillet over medium heat. Add the panko and cook, stirring frequently, for 2 to 3 minutes, until golden.
- Transfer the crumbs to a bowl right away to stop the toasting process. Stir in the thyme and a pinch of salt. Cool for 10 to 15 minutes, then stir in the Parmigiano Reggiano.
- Set aside until you're ready to serve.
Make the Mushroom Sauce
- Melt the butter with the olive oil in a medium skillet over medium-high heat. Add the chopped onion and cook for 3 to 5 minutes, until it starts to soften.
- Add the mushrooms and cook for 6 to 8 minutes, stirring occasionally, until their released liquid has evaporated and they’re browned.
- Stir in the minced garlic and thyme and cook for 30 seconds, until fragrant. Pour in the sherry and scrape up the browned bits from the bottom of the pan. Cook for 1 to 2 minutes, until the sherry has evaporated.
- Stir the flour into the mushroom mixture and cook for 1 minute.
- Gradually stir in the stock until smooth, scraping up any flour or brown bits on the bottom of the pan. Stir in the cream, Dijon, and ¼ teaspoon black pepper. Bring to a bubble, then reduce the heat and simmer for 5 to 6 minutes, stirring occasionally, until the sauce coats the back of a spoon.
- Stir in the Parmigiano and gently simmer until the cheese is melted and the sauce thickens. Taste and season with salt, if needed (see Note 3). If the sauce becomes too thick to pour, thin it with a splash of stock.
To Serve
- Arrange the green beans on a large platter and spoon the sauce over the top. If you’re using a smaller platter, layer the beans and sauce. Sprinkle with the breadcrumbs just before serving.
Notes
Nutrition Estimate
Nutrition information is automatically calculated, so should only be used as an approximation.
Please note that our recipes have been developed using the US Customary measurement system and have not been tested for high altitude/elevation cooking and baking.
