Name: Green Bean Casserole made with Sourdough Starter
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Ingredients: 24 oz. frozen green beans (thawed); 2 1/2 cups fried onions (divided); 1/4 cup sourdough starter discard (If using active sourdough starter, stir it down before measuring.); 8 oz. mushrooms (finely diced); 2 tablespoons butter; 1/2 cup chicken broth; 1 1/3 cup milk; 1 teaspoon garlic powder; 1 teaspoon onion powder; 1 teaspoon salt; 1/4 teaspoon black pepper; 1/8 teaspoon celery seeds; 1/2 cup grated parmesan cheese

Make this easy green bean casserole from scratch using frozen green beans and leftover sourdough starter. It takes just 20 minutes to prep and 30 minutes in the oven. With a creamy sauce made from scratch and crispy fried onions on top, this dish is sure to be a hit at your holiday table!

A baked green bean casserole made with sourdough starter.

A holiday table is just not complete without a savory green bean casserole. It's probably the holiday dish I look forward to the most!

Instead of using cream of mushroom soup, you'll make a delicious mushroom cream sauce with leftover sourdough starter.

We've taken our recipe for condensed cream of mushroom soup made with sourdough starter and added more milk and parmesan cheese. It's quick and simple to make with just a few pantry ingredients. It creates a creamy, flavorful base, perfect for casseroles and more! Who knew sourdough starter could be so versatile, beyond just bread?

The flour in the sourdough starter replaces the traditional flour used to make a roux, adding a unique flavor while still thickening the sauce for the green bean casserole.

Just like our hashbrown casserole and loaded mashed potato casserole, it's a classic Thanksgiving side dish that everyone looks forward to year after year!

Ingredients

frozen green beans: Fresh green beans can be used in this recipe. Wash and cut the green beans, and blanch them in boiling water for 5 minutes. (You could also use canned green beans that have been drained.)
mushrooms: Button mushrooms are affordable and readily available in most grocery stores, making them a convenient choice for this green bean casserole. You can also use baby portobello mushrooms, which add an earthier taste to the dish. Either option works great!
french-fried onions
roux: The roux for this dish is made using our homemade condensed cream of mushroom soup recipe. If you don't have a sourdough starter, replace the roux ingredients with 1 can of condensed cream of mushroom soup and add 1 cup of milk and ½ cup of grated parmesan cheese.
salt, pepper, garlic powder, onion powder, and celery seeds

How to make the best green bean casserole recipe

Transfer the frozen green beans to your refrigerator overnight to thaw or take them out a few hours before you start cooking.
Move the oven rack one space above the middle slot and preheat your oven to 375°F (190°C).
Lightly grease a 9" x 13" casserole dish with butter or cooking spray and set aside.
Wash the mushrooms and chop them finely.

Step 1: Prepare the green beans.

Place the thawed green beans in a large microwave-safe bowl and cook on high for 3 minutes, aiming for a crisp-tender texture. The green beans will continue to soften as the casserole bakes.

If you don't have a microwave, boil the green beans in water for 2-3 minutes, drain, and transfer to a large bowl.

Cream of mushroom soup with milk in a saucepan.

Step 2: Make the cream of mushroom soup sauce.

Melt the butter over medium heat in a medium pot.

Add the mushrooms and cook until they have released most of their liquid, about 5-6 minutes. Stir in the seasonings, sourdough starter, and parmesan cheese, whisking continuously until the mixture thickens, about 30-60 seconds.

To avoid lumps, gradually whisk in the broth, adding a tablespoon at a time. Once smooth, whisk in the milk and continue to whisk for 2-3 minutes, or until the soup has thickened slightly. Taste and adjust seasonings if needed.

Green bean casserole ingredients in a bowl.

Step 3: Mix the components.

Pour the sauce into the bowl of green beans and add one cup of fried onions. Stir everything together until the green beans are well coated with the creamy sauce and the fried onions are evenly distributed.

Green bean casserole ingredients in a baking dish.

Step 4: Assemble the casserole

Transfer the green bean mixture to the casserole dish, spreading it out evenly.

Sprinkle the remaining fried onions over the green beans to create a crispy, flavorful topping.

Step 5: Bake

Bake the casserole for 30 minutes or until bubbly and golden brown on top.

Baked green bean casserole made with sourdough starter in a baking dish after baking.

How to Store

How to make ahead of time

Green bean casserole can be prepared up to 2 days in advance and stored in the refrigerator. To do this, assemble the casserole in a baking dish, cover it with foil, and refrigerate. When you're ready to bake, keep in mind that it will take longer than the original instructions to heat through if it's cold from the fridge. Just add a few extra minutes to the bake time and keep an eye on it!

How to freeze

Assemble the green bean casserole in a freezer-safe dish. Wrap it tightly with two layers of foil and store it in the freezer for up to one month. When you're ready to bake, you can either bake it directly from frozen or after thawing it in the fridge overnight. If baking from frozen, allow extra baking time to ensure it's heated through.

How to store leftovers

Store any leftovers in an airtight container in the refrigerator for up to 4 days. To reheat, you can use either the microwave or the oven. If using the oven, bake at 350°F (176°C) until warmed through for a crispier texture.

more holiday recipes

Honey Glazed Carrots

Roasted Brussels Sprouts and Butternut Squash with Maple Dijon Dressing

Pumpkin Mac and Cheese

Corn Casserole

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