Every Thanksgiving, oven space is at a premium. This crockpot green bean casserole frees up a rack. Instead of canned soup, we make a quick homemade mushroom sauce. Let the slow cooker handle the rest. All that is left for you is to top it with crispy onions just before serving. It makes the busiest cooking day of the year a little easier.
If you want to free up some oven space this Thanksgiving and Christmas, this slow cooker green bean casserole is for you!
We are skipping the canned green beans and cream of mushroom soup and instead using fresh green beans in a simple homemade sauce.
The result is a creamy, rich, and oh-so-delicious side dish your family is going to love!
Looking for more ways to enjoy green beans? Don’t miss my Balsamic Green Beans, Green Bean Casserole with Frozen Green Beans, Oven Roasted Green Beans, and Instant Pot Green Beans,
Ingredient Notes
Make sure you use fresh green beans here. When I tested it, canned green beans turned into mush. Frozen ones add excess moisture. If you need to use frozen, make sure you pat them dry. Know your sauce will be a little thinner.
I like the way Gruyere melts here and takes on an elevated flavor in this crock pot green bean casserole. You could sub in Parmesan or cheddar if you prefer. Just make sure you grate it yourself. Pre-shredded is coated to keep it from clumping, and unfortunately this prevents a smooth melt.
Use regular flour or a gluten-free blend if you need it. If you are gluten-free, double-check that your french-fried onions are gluten-free because many brands aren’t.
Half and half gives this recipe for green bean casserole in the crock pot a nice balance of richness, though whole milk will lighten it, and heavy cream will make it extra indulgent.
Tips and Testing Notes
- For the freshest flavor, choose bright green beans that are firm and free of blemishes. Trim the ends before placing them in the slow cooker.
- To save time, slice mushrooms and onions the night before and store them in the fridge.
- Make Ahead: In my kitchen, I make the mushroom sauce the night before and keep it in the fridge. The morning of, I dump the beans in the crock, pour the sauce over, and turn it on. One less thing on the big day
- Keep a close eye on the casserole during the last hour of cooking to avoid overcooking the green beans.
- Store leftovers in an airtight container. They will keep in the fridge for about three days. I recommend reheating in the microwave.
- When I tested this the first time, I stirred raw flour straight into the broth and it clumped into little dumplings. Cooking the flour with the mushrooms and butter for a full minute first is what gives you a smooth sauce.
Step by Step
Make sure you check out the recipe card below for the full crock pot green bean casserole recipe.
Crockpot Green Bean Casserole with Fresh Green Beans (No Canned Soup)
Equipment
Ingredients
- 2 pounds fresh green beans trimmed and cut into 1” pieces
- 2 tablespoons unsalted butter
- 1 pound white mushrooms sliced
- 1 onion sliced thin
- ¼ cup all-purpose flour or gluten-free
- 1 teaspoon sea salt
- ¼ teaspoon freshly ground black pepper
- ⅛ teaspoon cayenne pepper
- 2 cups chicken broth
- 2 ½ cups half and half
- 1 cup shredded Gruyere cheese
- 1 ½ cups fried onions about 3 ounces
Instructions
- Place the green beans in the bottom of your slow cooker.
- Melt the butter in a large saute pan over medium-high heat. Add the mushrooms and cook for 5 minutes. Add the onions and cook for another 5 minutes. Sprinkle with the flour, salt, pepper, and cayenne pepper.
- Cook for 1 minute. Stir in the broth, a little at a time. Bring to a simmer, and then whisk in the half and half. Reduce to medium-low, and cook for 10 minutes, until the sauce is thick.
- Pour the sauce over the green beans, and top with the cheese.
- Cover and cook over low heat for 4 to 6 hours.
- Top with the fried onions just before serving.
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