Green bean casserole is a Southern classic, and this slow cooker version makes it even easier.

Green bean casseroles fill a special place in the holiday meal plan assortment. It's both a vegetable side dish (necessary to balance out all those cakes and pies) and a deeply comforting dish (thanks to creamy sauces and loads of cheese). But the typical green bean casserole is baked in the oven, real estate in the average cook's kitchen that is highly prized and sought after during holiday cooking.

That's why this slow cooker green bean casserole recipe is such a great addition to holiday cookbooks. Not only does it check all the boxes for this casserole—creamy, comforting, and fresh—but also it's made in a slow cooker or Crockpot, saving your oven for other tasks.

What's more, this Crockpot slow cooker green bean casserole is a bit different from your standard green bean casserole. In place of cans of mushroom soup, we use jarred Alfredo sauce for the same decadent mouthfeel but with a more elevated flavor. Water chestnuts and mushrooms provide a yin-yang of textures: toothsome, a bit crunchy, and a nice contrast to the creamy sauce. You'll still find the classic casserole toppers—French fried onions—because they're quite simply a requirement. But to up the crunch factor (and, of course, make this dish more Southern) we've added some chopped pecans.

Keep reading to learn more about this slow cooker green bean casserole, and if you make it, be sure to leave us a recipe review so we'll know how well you enjoyed it.

Green Beans This Crockpot green bean casserole calls for frozen green beans. They hold their texture and snap better than canned green beans. You do not need to thaw them before making the dish.

Alfredo Sauce Instead of cream of mushroom soup, we're calling on jarred Alfredo sauce for the creamy factor you know and expect in a green bean casserole. Alfredo sauce is typically made with Parmesan cheese, milk, butter, and salt and pepper, which keeps the flavors in this casserole simple and satisfying. You'll add more Parm later to amp up that cheesy flavor.

Mushrooms If you like the earthiness that cream of mushroom soup provides most green bean casseroles, you'll be glad to see mushrooms in this slow cooker version, too. We call for jarred mushrooms in this recipe, but fresh mushrooms will still turn tender and delicate and add a hint of earthiness to the final dish's flavor.

Water Chestnuts This ingredient is optional, but once you try it, you'll understand why it's common in most traditional green bean casseroles. Water chestnuts, as the name might imply, are aquatic vegetables that are a bit sweet and nutty. But they're really valued for their crunch factor.

French Fried Onions No green bean casserole is complete without French fried onions, and we surely didn't skip them in our recipe. In fact, we doubled up the amount and put some in the green bean mixture while is cooks and some on top for both a beautiful presentation and a nice crispness.

Parmesan Cheese Echoing the flavors of the Alfredo sauce, this recipe calls for Parmesan cheese. If you can, splurge for the block and grate your own. Bagged Parm is often coated in a powder that keeps it from melting beautifully.

Pecans For additional crunch (and a Southern touch), we're adding pecans to this green bean casserole. They'll get toasted at the end with the second half of French fried onions so they're fragrant and flavorful just before serving.

This recipe is made in a four-quart slow cooker. You could double it and make it in a larger eight-quarter Crockpot if you have one.

Spray the slow cooker's insert with cooking spray. Then, in a large bowl, combine the frozen green beans, Alfredo sauce, diced water chestnuts, mushrooms, Parmesan cheese, pepper, and half of the French fried onions. Spoon the green bean mixture into the greased slow cooker insert.

Set a timer for 4 hours and 30 minutes, and cook the green bean mixture on low. Resist the urge to remove the lid while the green bean casserole cooks. Every time you do, it takes the appliance a significant amount of time to get back up to cooking temperature. Look through the lid, and after 4 hours, start checking for signs of bubbles. Once the casserole is bubbling, it's nearly finished.

Add pecans and remaining French fried onions to a medium skillet, and heat slowly over medium-low heat. Stir every few seconds, and cook for 1 to 2 minutes or until the pecans and French fried onions are toasted. They will also start to release odors and become fragrant as they heat and toast.

Once the toppings are fully toasted, you can sprinkle them on the green beans. Or, if you're preparing to serve the casserole, spoon the beans into a serving dish, and then sprinkle on the French fried onions and pecans.

If you're cooking on low, plan for 4 1/2 hours cook time. You can bump the temp up to high for an hour to shave off some of the cook time, but watch for signs of burning, and turn it back to low after an hour.

If you like the look of this green bean casserole but need it cooked faster, try this Old-School School Green Bean Casserole.

Whether this is your first casserole, or you've made dozens, these common questions might help you make a better casserole.

A watery green bean casserole could mean a few things. First, make sure you drain the cans of water chestnuts and mushrooms. The extra water in these ingredients is not necessary.

Secondly, frozen green beans can release some water as they thaw. If you're worried, you can thaw the green beans for about an hour, and then pat them dry before mixing them with the other ingredients to begin the recipe. But the moisture released is usually so minimal it won't create a soggy problem.

Absolutely, you can cook a green bean casserole two to three days before you plan to serve it. Then, heat it slowly in the oven to get it ready to serve. Save the final layer of pecans and French fried onions until it's nearly time to eat.

Alternatively, you can mix together all the ingredients for this green bean casserole, and store them in an airtight container or the slow cooker crock (covered with plastic wrap). Then, when you're ready to cook the casserole, put all of the green beans in the slow cooker crock, and cook it.

Read More: Can You Make Green Bean Casserole Ahead of Time?

Yes, canned or fresh green beans can be substituted for the frozen ones in this recipe. However, keep a few things in mind.

If you use canned, be sure to drain them well. You might also need to reduce the cook time because they will be tender and heated through quickly.

If you use fresh green beans, you may need to add a bit more cook time to get them tender. Frozen green beans are blanched before they're frozen, so they've already been partially cooked. That's why we like using them in this recipe—they cook faster. But fresh can be used, too. Just be sure to trim them before mixing them with the other ingredients.

Need more vegetable side ideas? Check out these green bean recipes that complement any dish.

Editorial contributions by Kimberly Holland.

Stir together first 6 ingredients and half of French fried onions; spoon mixture into a lightly greased 4-qt. slow cooker.

Cover and cook on LOW 4 1/2 hours or until bubbly.

Heat pecans and remaining half of French fried onions in a small nonstick skillet over medium-low heat, stirring often, 1 to 2 minutes or until toasted and fragrant; sprinkle over casserole just before serving.