Slow Cooker Green Bean Casserole

slow cooked green bean casserole in a slow cooker.

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Slow-cooker green bean casserole made from scratch with green beans, mushrooms, and a creamy cottage cheese sauce, then finished with crispy Parmesan panko. An easy holiday side dish that saves valuable oven space.

Prep Time15

Cook Time3 20

Total Time3 35

Course: Side Dish

Cuisine: American

Diet: Halal, Vegetarian

Skill Level: Beginner

Servings: to 8 servings

Author: Rena Awada

Ingredients

Green Bean Casserole:

2 pounds frozen green beans thawed and thoroughly patted dry
1 tablespoon olive oil
8 ounces cremini mushrooms finely sliced
1 small white onion finely diced
3-4 cloves garlic minced
½ teaspoon dried thyme
½ teaspoon fine sea salt
¼ teaspoon freshly ground black pepper

Creamy Cottage Cheese Sauce:

2 cups full-fat cottage cheese
¾ cup whole milk
1 cup shredded sharp cheddar cheese
¼ cup finely grated Parmesan cheese
1 tablespoon cornstarch
1 tablespoon Dijon mustard
½ teaspoon garlic powder
½ teaspoon onion powder
¼ teaspoon dried thyme
¼ teaspoon freshly ground black pepper
1 pinch ground nutmeg
¼ teaspoon fine sea salt or to taste

Crispy Panko Topping

1 tbsp butter
¾ cup panko breadcrumbs
2 tbsp finely grated Parmesan cheese
¼ tsp garlic powder
1 pinch salt
freshly ground black pepper

Instructions

Prepare the Green Beans

Make sure the 2 pounds frozen green beans (thawed) are very well drained and patted dry. Set aside.

This is particularly important in the slow cooker because excess water can thin the creamy sauce.

Cook the Mushrooms

Heat the 1 tablespoon olive oil in a large skillet over medium-high heat.
Add the 8 ounces cremini mushrooms (finely sliced) and 1 small white onion (finely diced) and cook for 6-8 minutes, stirring occasionally, until the mushrooms have released their liquid, the moisture has mostly evaporated, and the vegetables are lightly golden.
Add the 3-4 cloves garlic (minced), ½ teaspoon dried thyme, ½ teaspoon fine sea salt, and ¼ teaspoon freshly ground black pepper. Cook for another 30-60 seconds, until fragrant. Remove from the heat.

Make the Cottage Cheese Sauce

Add the 2 cups full-fat cottage cheese, ¾ cup whole milk, 1 cup shredded sharp cheddar cheese, ¼ cup finely grated Parmesan cheese, 1 tablespoon cornstarch, 1 tablespoon Dijon mustard, ½ teaspoon garlic powder, ½ teaspoon onion powder, ¼ teaspoon dried thyme, ¼ teaspoon freshly ground black pepper, 1 pinch ground nutmeg, and ¼ teaspoon fine sea salt to a high-speed blender.
Blend for 1-2 minutes, until completely smooth and creamy with no visible cottage cheese curds remaining. The sauce will be rather thick.
Taste and adjust the seasoning. The sauce should taste slightly more intensely seasoned than you think it needs to because the green beans will mellow the flavors.

Assemble

Lightly grease the inside of a slow cooker.
Add the green beans and sautéed mushroom mixture. Pour the cottage cheese sauce over everything and gently toss until the beans are evenly coated.
Cover and cook on LOW for 4-5 hours or HIGH for 2-3 hours, until the green beans are tender and the sauce is hot and creamy.

Avoid repeatedly opening the lid while it cooks.

Once done, gently stir the casserole. If the sauce seems slightly loose, leave the lid off for 10-15 minutes before serving. It will thicken further as it cools slightly.

Make the Crispy Panko

Make the topping shortly before serving.
Melt the 1 tbsp butter in a skillet over medium heat. Add the ¾ cup panko breadcrumbs and cook for 3-5 minutes, stirring frequently, until deeply golden and crisp.
Remove from the heat and stir in the 2 tbsp finely grated Parmesan cheese, ¼ tsp garlic powder, a small pinch of 1 pinch salt, and some freshly ground black pepper.

Finish

Transfer the green bean casserole to a serving dish or leave it directly in the slow cooker. Scatter the toasted Parmesan panko generously over the top immediately before serving warm.

Notes

Make sure the frozen green beans are completely thawed and very well dried before adding them to the slow cooker.
Cook the mushrooms until they release their liquid and most of the moisture has evaporated.
Use full-fat cottage cheese for the creamiest sauce.
Blend the cottage cheese sauce until smooth.
Don't add the panko topping until just before serving, or it will lose its crunch.
Crispy fried onions can be used instead of the panko topping for a more traditional green bean casserole.
Store leftovers in the refrigerator for up to 4 days.

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