Easy Slow Cooker Green Bean Casserole

Ingredients You’ll Need, Substitutions & Notes

Please check the recipe card at the bottom of the post for exact quantities and detailed instructions (scroll down).

• Fresh green beans: You use fresh or frozen. I prefer fresh.
• Smoked gouda: I like to use smoked gouda because it adds a delicious smoky flavor to the casserole. However, you can also use shredded cheddar, white cheddar, or mozzarella, if you prefer.
• Can condensed cream of mushroom: Homemade (see instructions below) or store-bought.
• Milk: For cooking and baking, I like to use whole milk. However, you can use any milk you have handy. You can substitute milk for chicken or vegetable stock.
• Leeks: These have a sweet, oniony flavor that adds depth to the casserole. Don’t skip them!
• Chestnuts: This is optional but highly recommended.  I love the crunch of the water chestnuts.
• Dijon mustard: For an extra layer of flavor!

How To Make Homemade Condensed Cream Of Mushroom

If you don’t want to use a canned soup, simply place 1/2 cup onions, 1 garlic clove,  and 8 oz mushrooms into a food processor and pulse a couple of times until small chunks. Melt the 4 tablespoons of butter in a saucepan. Add in the vegetable mixture, season with salt and pepper to taste; cook for 5 minutes. Add in the 4 tablespoons of all-purpose flour and stir the ingredients together well for about a minute to let the flour cook a bit. Add in the 1/2 cup evaporated milk and 1/2 cup chicken broth; cook until thickened.

Overview: How to Make Green Bean Casserole In The Slow Cooker

Please check the recipe card at the bottom of the post for exact quantities and detailed instructions (scroll down).

Step 1 – Throw Everything in the Slow Cooker

In the slow cooker, stir together the green beans, cheese, soup, milk, leeks, chestnuts, and mustard.

Step 2 – Slow Cook

Cover and cook on HIGH for 2 1/2 to 3 hours or on LOW for 5 to 6 hours.

Step 2 – Add Toppings

Sprinkle with toppers, if using, just before serving.

Green Bean Casserole Topping Ideas

Bacon. Crispy and savory crumbled bacon is a delicious topping for this casserole. Place 4 -5 bacon slices in a large skillet. Cook over medium-high heat until evenly brown and crispy. Drain, crumble, and add them to the top of the casserole just before serving.

French Fried Onion. This is the traditional topping for this dish, and we love it. Make sure to add them just before serving. They won’t stay crispy if you add them right into the crockpot.

Breadcrumbs and Parmesan. Cook the casserole as instructed in the recipe. Then, when it is ready, transfer it to an oven-safe dish. Combine 1/2 cup breadcrumbs, 1/3 cup parmesan cheese, 1/4 teaspoon garlic powder, and 1 teaspoon dried parsley. Sprinkle over the green bean casserole. Broil in the oven for 2-3 minutes until the topping is golden. 

Ritz Crackers. Cook the casserole as instructed in the recipe. Then, when it is ready, transfer it to an oven-safe dish. Crush 24 Ritz crackers. In a small bowl, toss together cracker crumbs, 1 tablespoon of butter, and 1/2 cup of shredded cheddar cheese. Top beans with the cracker mixture. Broil in the oven for 2-3 minutes until the topping is golden. 

Nuts. If you don’t have any nut restrictions, you can top your casserole with ¼ cup of sliced almonds, pecan, or walnuts.

Substitutions & Additions

• Cheese. Instead of smoked Gouda, you can use shredded cheddar, white cheddar, or mozzarella.
• No cans for me, please! If you don’t want to use a canned soup, simply cook 3 tablespoons unsalted butter and 3 tablespoons flour until it forms a paste, then whisk 1 cup milk and 1/2 cup shredded cheddar until smooth. Add this mixture to the potatoes instead of the canned cheddar soup.
• Make it your own!! Change toppers according to your family’s taste. Some ideas: potato chips, nuts, mini cheese crackers, crisp bacon, mini pretzels, panko breadcrumbs, etc.
• Not a big chestnut fan? No problem!! Substitute chestnut for mushrooms, red pepper, or green onion –whatever floats your boat.

Storing & Freezing Instructions

Store: If you have leftovers, simply cover and store them in the fridge for up to 3 days.

Freeze: I don’t recommend freezing this casserole. The texture of the creamy sauce will change once thawed.

Reheat: I recommend reheating any leftovers in the oven so that the fried onions stay crispy. Just place the casserole in the oven at 350°F for 15 to 20 minutes, or until it’s warm throughout. You can cover it with foil if the fried onions start to brown too fast. If you prefer, you can reheat it in the microwave for 30 to 45 seconds.