While I can’t deny the ease of opening a can of green beans and a can of mushroom soup and dumping them into a baking dish, taking a little extra time to prepare green bean casserole from scratch is well worth it and exponentially more delicious. Though green bean casserole is typically cooked in the oven, this version is made in a slow cooker, freeing up space it your oven. In the slow cooker, the green beans become very tender and soaked in the umami-packed mushroom cream sauce (made from scratch, of course).
The Flexibility of a Slow Cooker
I love my slow cooker—it frees my hands (and oven) for hours, and the cook time is always forgiving. Fill it with ingredients, put the lid on, and let it do its thing. It doesn’t get much easier than that!
Most slow cookers have three settings: high, low, and warm. I start most slow cooker recipes on high and reduce to low if I want to draw out the cook time. This recipe needs at least 2 hours on high to get the green beans tender, but cooking it for longer makes it even better—the flavors meld and the sauce cooks down and concentrates a bit more.
Then, I shift it to warm when everything inside is fully cooked, but I want to keep it warm until ready to serve. On the warm setting, the green bean casserole will hold for 4 to 5 hours, which is great for when your guests graze on the food throughout the party.
Using Fresh, Blanched Green Beans
You can use frozen green beans, but I recommend using fresh, if you have them. You will need to blanch them before adding them to the slow cooker.
What is blanching? It means cooking the green beans in boiling water for a few minutes until they’re vibrantly colored and crisp-tender, then shock them in an ice bath—this stops any further cooking from residual heat and locks in the flavor.
You do not need to blanch frozen green beans.
A Simple Homemade Mushroom Cream Sauce
I have a friend who is a diehard fan of classic green bean casserole—only store-bought French’s Fried Onions sprinkled on top scratch that nostalgic itch for her. But even she admits that homemade mushroom cream sauce is a game changer and far more delicious than the canned stuff. And it couldn’t be simpler to make.
Start by cooking your mushrooms in a bit of butter. I typically use cremini mushrooms—they are small, tender, and have a subtle meaty flavor., You can use a mix of mushrooms: button, portobello, chanterelle, and even a few morels would be delicious. I’d avoid shiitake mushrooms because they are too chewy for this recipe.
Once the mushrooms are cooked, add a bit of flour to make a roux—a combination of butter and flour used to thicken the sauce—and then add some chicken stock and cream. That's it!
The mushroom sauce can be made ahead and stored in the fridge for up to 5 days or in the freezer for 2 months.
Fry Your Own Shallots
I prefer crispy shallots to onions on top of my green bean casseroles—they are crispier when fried and don't even need a batter. without a batter.
The trick to ultra crispy shallots is to slice them as thinly as possible. Start them in cold oil. They'll get crispy in no time, so stir them regularly and keep a close eye on them. Once they become golden brown, drain the fried shallots on a paper towel. And try not to snack on too many while your casserole cooks!
The fried shallots can be stored in an airtight container for up to 1 month.
Save the shallot oil. It’s delicious for everything from sautéing vegetables to whisking into salad dressing.
Don’t have time to fry your own shallots? I keep a jar of store-bought shallots in my cupboard at all times. I find them at my local Asian grocery store. Of course, French’s Fried Onions always works too.
Swaps and Substitutions
- This recipe uses chicken stock, but you can easily make it vegetarian by swapping out vegetable stock or, even better, mushroom stock.
- Looking for a vegan casserole? Use vegan butter, like Earth Balance, and unsweetened cashew milk instead of the half and half.
- Is it a green bean casserole without green beans? Probably not. But blanched broccoli or cauliflower would be delicious swaps regardless.
For the Love of Green Beans
Slow Cooker Green Bean Casserole
2 pounds green beans, trimmed and cut into 1 1/2-inch pieces
3 tablespoons unsalted butter, divided
1 pound sliced cremini mushrooms
2 teaspoons salt, plus more to taste
3 garlic cloves, minced
1 tablespoon fresh thyme leaves
Large pinch crushed red pepper flakes
1/4 cup all-purpose flour
1 1/2 cups chicken stock
1 1/2 cups half and half
1 teaspoon soy sauce
1 teaspoon red wine vinegar
A few cracks freshly ground black pepper
For the crispy shallots
1 pound (about 8 medium) shallots, very thinly sliced
2 cups vegetable oil
Prep for blanching the green beans:
Fill a large stock pot or Dutch oven with heavily salted water and set on the stove to boil over high heat.
Fill a large mixing bowl with ice water and set aside (this is your ice bath).
Blanch the green beans:
Once the water comes up to a boil, add the green beans and cook until bright green and just tender, 4 to 5 minutes.
Drain the green beans and immediately plunge them into the ice bath. Once cooled, drain the green beans again and set aside.
Sauté the mushrooms:
In the same pot or Dutch oven, melt 2 tablespoons butter over medium heat. Once melted, add the mushrooms and the salt. Cook the mushrooms until they’ve softened and any water they’ve released has cooked away, about 8 minutes.
Add garlic and red pepper flakes:
Add the remaining butter, garlic, thyme leaves, and red pepper flakes, and cook until the garlic is fragrant, about 1 minute.
Finish the mushroom sauce:
Sprinkle the flour over the mushrooms and stir to coat. Slowly add the chicken stock and half and half, making sure to scrape the bottom of the pot to scrape up any stuck-on bits. Cook, stirring frequently, until the sauce has reduced and thickened, about 10 minutes.
Add the soy sauce, red wine vinegar, and a few crack of black pepper. Stir well and taste the sauce, you may want to add more salt.
Assemble the casserole in the slow cooker:
Add the blanched green beans and mushroom sauce into the slow cooker. Stir until the green beans are coated in the sauce. Cover with a lid and cook on high for 2 1/2 hours, until the green beans are soft and tender, but not mushy.
Prep for frying:
Line a large plate with several pieces of paper towel. Set a fine-mesh strainer over a heat-proof bowl. Set both aside.
Fry the shallots:
In a medium saucepan, combine the sliced shallots and vegetable oil. Cook on medium-low heat, stirring frequently. The shallots will soften first and then turn golden brown. Continue to fry until the shallots are a dark golden brown, about 20 minutes. Carefully strain the shallots through the fine-mesh strainer and then spread them out on the prepared paper-towel lined plate to cool.
Reserve the flavorful shallot oil for dressings and cooking.
Serve the casserole:
Once the green beans are cooked, stir them well and set the slow cooker to warm. Scatter the fried shallots on top and serve.
I store my leftovers directly in the slow cooker—just put the lid on and clear some room in the fridge—for up to 5 days.
To reheat, return the pot to the base and heat on low for about 1 hour.
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|Nutrition Facts (per serving)|
|Servings: 8 to 10|
|Amount per serving|
|% Daily Value*|
|Total Fat 19g||24%|
|Saturated Fat 6g||29%|
|Total Carbohydrate 21g||8%|
|Dietary Fiber 5g||16%|
|Total Sugars 9g|
|Vitamin C 13mg||65%|
|*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.|