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).
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Why You’ll Love This Easy Crockpot Green Bean Casserole Recipe
- The Homemade Filling is Truly Delish! You have two options for green bean casserole: canned cream of mushroom soup mixture (like the Campbell’s crockpot green bean casserole recipe), or an easy homemade mushroom filling. Making the creamy sauce for green bean casserole from scratch is 100% worth it! This mushroom filling is easy, luscious, and anything but bland.
- It Doesn’t Use any Oven Space. Outsourcing side dishes to the slow cooker is a pro-holiday move. No matter the size of the gathering, we always run out of oven space and the slow cooker is a brilliant solution! This green bean casserole (and Crockpot Scalloped Potatoes, Crock Pot Stuffing, or Crockpot Wild Rice Stuffing) is the perfect way to keep that oven free for Thanksgiving Turkey.
- It Uses Fresh Green Beans. Like my Healthy Green Bean Casserole, this version uses fresh green beans. Their texture and flavor are superior, and aside from trimming them, they don’t create any extra prep work (no blanching required). Fresh green beans hold up better in the slow cooker than frozen or canned, so you’re not left with a gummy, goopy casserole.
How to Make The Best Crockpot Green Bean Casserole
- Fresh Green Beans. 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 a fresh green bean casserole.
- Mushrooms + Onions. No cream of mushroom soup here! Real, fresh mushrooms and onions are sauteed in butter until tender and flavorful. Mushrooms and onions also boost the casserole’s nutrition with their antioxidants and vitamins.
- Milk. To keep this a healthy green bean casserole crockpot recipe, I skipped the cream/half-and-half and used regular milk. The filling still tasted rich and just the right amount of decadent.
- Flour. Helps thicken the casserole filling so it’s creamy and luscious.
- Sherry Vinegar + Nutmeg. 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!
- Cheddar Cheese. I took a note from some classic Midwest versions of this recipe and made this a crockpot green bean casserole with cheese. DELISH.
- Crispy Onions. While you can make your own crispy onions at home, I used French’s fried onions. The crispy onions add delightful texture and are scrumptious paired with the creamy mushroom sauce and green beans.
- Trim and Cut the Green Beans. Add them to a slow cooker (a 6-quart is best to ensure even cooking).
- Sauté. Cook the onion and mushrooms in butter.
- Stir. Add the flour, and let it cook for a couple of minutes.
- Pour in the Milk. Add the spices. Cook and stir until bubbly. Add the vinegar.
- Pour the Sauce Over the Beans. It’s almost time to cook!
- Stir and Cook. Cook on LOW for 3 to 5 hours. Just before serving, add the cheese. Top with crispy onions. DIG IN!
- To Make Gluten Free. This is not a gluten free crockpot green bean casserole as written. However, I think you could swap the all-purpose flour for a 1:1 gluten free flour to make it gluten free. Be sure to check your fried onions too.
- To Make Vegan. I have not tried to make this a vegan crockpot green bean casserole, but if you want to experiment, you’ll need to use dairy-free milk, cheese, and butter.
- 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 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 mix up green bean casserole the night before too. 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 this leftover crock pot green bean casserole recipe into a hearty main dish. Enjoy crockpot green bean casserole with chicken or leftover turkey or ham.
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 after you make this cheesy green bean casserole.
Recipe Tips and Tricks
- NO Canned Green Beans. If you aren’t able to use fresh green beans, opt for frozen, cut green beans instead. Canned green beans will end up mushy.
- Don’t Skip the Sherry Vinegar. With its mild acidity and wonderfully nutty flavor, sherry vinegar subtly elevates this dish. It’s worth grabbing a bottle for this casserole (and any of these recipes that use it)!
- Make It Ahead. Let this casserole be your holiday meal MVP! Not only does it free up your oven space, but it also can be made in advance. See the “Make Ahead Tips” box above for ideas.
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
- 1/2 teaspoon black pepper
- 1/8 teaspoon ground nutmeg
- 1 tablespoon sherry vinegar
- 1 cup shredded cheddar cheese or gruyere cheese*
FOR THE TOPPING:
- 1 1/2 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 on 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°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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Frequently Asked Questions
If your casserole is soupy, it’s likely because there was excess water in your ingredients. If you’re washing them first, sure you allow the green beans and mushrooms to dry completely before you begin the recipe. Also, a soupy green bean casserole could mean there wasn’t enough flour added.
To rectify a soupy casserole situation, try adding in extra flour. Start with just a little, then add more if needed. It’s also important to note that green bean casserole will thicken as it cools, so if your casserole isn’t too soupy, you may want to let it sit awhile to see if that helps.
As far as green bean casserole goes, this recipe is relatively healthy. It’s packed with fiber, vitamin C, and protein from the green beans, and the cheese brings some calcium. Dig in and enjoy!
Frozen, cut green beans are the next best option to fresh. If you’d like to save some time, you can purchase a bag of cut, frozen 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.
AVOID canned green beans. 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. Green bean casserole is better with fresh green beans (or frozen), not canned.
No. 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.