This Crockpot Green Bean Casserole is everything that a green bean casserole can and should be (creamy, appropriately al dente, with a from-scratch flavor and addictively crunchy top) and exactly nothing that it shouldn’t be (mushy, overcooked to the point of destruction, bland). A legitimately tasty version of a time-honored side made easy in the slow cooker, this is the green bean casserole we all need!
I came to green bean casserole late in life.
After years of wondering how it became a seemingly obligatory part of Thanksgiving (why waste space on an overcooked casserole when you can pack in the Cornbread Stuffing, Healthy Sweet Potato Casserole, Brussels Sprouts Casserole, or any of these Thanksgiving recipes instead?), I finally decided to cook it myself and see if I could come up with a green bean casserole that merited its spot on the plate.
Guess what? I BELIEVE.
This Healthy Green Bean Casserole showed me the possibilities and is now mandatory in my personal Thanksgiving line up.
Today’s recipe is a slow cooker adaptation. I made a few tasty tweaks based on your feedback (like turning it into a crockpot green bean casserole with cheddar cheese—so good!) and streamlined the prep process so that you don’t have to blanch the green beans in advance.
Outsourcing side dishes to the slow cooker is a pro holiday move. No matter the size of the gathering, we always run out of space in the oven and the slow cooker is a brilliant solution!
Plus, the inherent make-ahead nature of the crock pot will make the day of less stressful too.
How to Make The Best Crockpot Green Bean Casserole
This green bean casserole breaks down into three key parts: the green beans, the creamy gravy, and the topping. Let’s explore.
Part 1: The Green Beans
When it comes to the green beans for green bean casserole, you have three choices: fresh, frozen, or canned.
- Fresh Green Beans. THE ONE YOU WANT. Fresh green beans are far less likely to overcook even after hours in the crockpot and have a crisp, delicious flavor. Trimming fresh green beans is quite possibly my least favorite kitchen task, and I am telling you, it is worth doing for fresh green bean casserole.
- Frozen, Cut Green Beans. The next best option. If you’d like to save some time, you can purchase a bag of frozen, cut green beans. Steam them according to the package instructions and pat them very dry before adding them to the slow cooker. They will be a little mushy, but certainly not inedible.
- Canned Green Beans. AVOID. Canned green beans will make your casserole mushy and inflict a metallic, stale flavor. If you haven’t liked green bean casserole in the past, the recipe likely used canned green beans.
While some crockpot fresh green bean casseroles call for blanching the green beans before adding them to the slow cooker, to me this took away the slow cooker’s ease.
After some playing around, I found by cutting the green beans into 1-inch pieces, I could cook them directly in the slow cooker without steaming or blanching. The green beans softened nicely, and we didn’t have any problems with hard pieces.
Part 2: The Creamy Mushroom Filling
Here, you have two options: canned cream of mushroom soup (like the Campbell’s crockpot green bean casserole recipe), or an easy homemade mushroom filling.
As with trimming green beans, making the creamy sauce for green bean casserole from scratch is 100% worth it!
This mushroom filling is easy, lusicious, and anything but bland.
- To keep this a healthy crockpot green bean casserole, I skipped the cream/half-and-half and used regular milk. The filling was still tasted rich and just the right amount of decadent.
- A splash of sherry vinegar and a touch of nutmeg make this filling shine. I had a hard time stopping myself from eating it right out of the pan!
- I took a note from some classic Midwest versions of this recipe and your comments and stirred cheddar cheese into the green bean casserole at the end. DELISH.
Part 3: The Topping
While I’m proud about making these crock pot green beans from scratch, there was one store-bought ingredient that my taste testers actually preferred: the canned French fried onions.
I skipped stirring the onions into the casserole and used sauteed fresh onions in the filling instead, but for the topping, the salty, crispy crunch hit the spot.
- Trim and cut the green beans. Add them to a slow cooker. 6-quart is best to ensure even cooking.
- Sauté the onion and mushrooms in butter.
- Stir in the flour, and cook for a couple minutes.
- Pour in the milk slowly, stirring constantly. Add the spices. Cook and stir until bubbly. Add the vinegar.
- Pour the sauce over the beans.
- Stir to coat. Cook on LOW for 3 to 5 hours. Just before serving, add the cheese.
- Top with crispy onions. DIG IN!
- To Store. Refrigerate the casserole in an airtight storage container for up to 4 days.
- To Reheat. Rewarm leftovers in a baking dish in the oven at 350 degrees F.
- To Freeze. Freeze green bean casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating. The crispy onions will become soggy (if using), but the casserole will still taste delicious.
Make Ahead Tips
Prepare the mushroom sauce up to 1 day in advance, and place it in an airtight storage container in the refrigerator. Trim and cut the green beans up to 2 days in advance, and store them in a separate container in the refrigerator.
You can also add the trimmed and cut green beans to a slow cooker, and stir them together with the mushroom sauce. Cover and refrigerate the slow cooker for up to 1 day, then finish the recipe as directed.
Turn leftover green bean casserole into a hearty main dish by stirring in some leftover turkey, ham, or chicken before reheating.
Recommended Tools to Make this Recipe
- Slow Cooker. This one switches to “warm” to deter overcooking.
- Saucepan. You’ll use this kitchen tool on repeat.
- Measuring Spoons. Since these are double-sided, you’ll have less to wash.
Crockpot Green Bean Casserole
FOR THE CASSEROLE:
- 2 pounds fresh green beans
- 2 tablespoons unsalted butter
- 1 medium yellow onion thinly sliced
- 16 ounces baby bella mushrooms thinly sliced
- 3 tablespoons all-purpose flour
- 2 cups whole milk a lower fat milk may curdle, so swap at your own risk; for more decadence, use part half-and-half
- 1 teaspoon kosher salt
- ½ teaspoon black pepper
- ⅛ teaspoon ground nutmeg
- 1 tablespoon sherry vinegar
- 1 cup shredded cheddar cheese or gruyere cheese*
FOR THE TOPPING:
- 1 ½ cups fried onions store bought or homemade; to make your own, see blog post above; about 3 ounces
- Trim the green beans and cut into 1-inch pieces (don’t be tempted to cut them larger than this, or your green beans will turn out too firm). Add them to a 5 or 6-quart slow cooker.
- Melt the butter in a wide saucepan over medium heat. Add onion and mushrooms. Cook, stirring occasionally, until the onion is soft and golden and the mushrooms brown and have given up their liquid, about 12 minutes.
- Sprinkle the flour over the top. Cook, stirring constantly, for 1 to 2 minutes more, until all of the flour turns golden and no white bits remain. The vegetables will seem dry.
- Slowly add the milk a few splashes at a time, stirring between each addition to prevent lumps from forming. Increase the heat to medium high. Stir in the salt, pepper, and nutmeg. Cook and stir, allowing the sauce to bubble gently, running a wooden spoon or rubber spatula along the bottom of the pan. Continue cooking and stirring for 6 minutes, then stir in the sherry vinegar. Cook 2 to 4 more minutes, until the sauce has thickened to resemble a creamy gravy. It should be clearly thicker than it was when you started, but still be loose enough to easily coat the green beans.
- Pour the sauce over the green beans.
- Stir to combine. Cook on LOW for 3 to 5 hours, until the green beans are pleasantly tender but still have a bit of crispness (i.e. are done but not mushy). The amount of cook time you need will vary based upon your slow cooker and your preference for how al dente you like the green beans. I recommend checking at the 3-hour mark to gauge their progress. We like our green beans pretty crisp, so I only let ours cook a little beyond 3 hours. If at 3-hours you'd like your green beans more done, give the casserole a stir, recover, and keep cooking until they reach your desired texture.
- Five minutes prior to serving, stir in the cheese. Recover, turn to WARM, and let cook 5 minutes to melt the cheese.
- Immediately before serving, if desired, transfer the green beans and sauce to a serving dish. Sprinkle the fried onions over the top (if you will be serving right out of the slow cooker, remove the lid, then sprinkle the onions on top of the green beans in the slow cooker). Enjoy hot!
- *I love either gruyere or cheddar here; gruyere is more intense and nutty and tastes classic with the nutmeg; cheddar is more “all-American”, so choose whichever one you and your family prefer.
- TO MAKE AHEAD: Prepare the mushroom sauce up to 1 day in advance, and place it in an airtight storage container in the refrigerator. Trim and cut the green beans up to 2 days in advance, and store them in a separate container in the refrigerator.
- You can also add the trimmed and cut green beans to a slow cooker, and stir them together with the mushroom sauce. Cover and refrigerate the slow cooker for up to 1 day, then finish the recipe as directed.
- TO STORE: Refrigerate the casserole in an airtight storage container for up to 4 days.
- TO REHEAT: Rewarm leftovers in a baking dish in the oven at 350 degrees F.
- TO FREEZE: Freeze green bean casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating. The crispy onions will become soggy, but the casserole will still taste delicious.
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