Homemade Green Bean Casserole (From Scratch Recipe)

This homemade green bean casserole is made completely from scratch with fresh green beans, creamy mushroom sauce, and crispy fried onions. Say goodbye to canned soup! This elevated version features fresh ingredients, rich umami flavor, and vibrant color that will make it the star of your Thanksgiving table. Once you try this recipe, you’ll never go back to the Campbell’s version.

Why You’ll Love This Green Bean Casserole Recipe

This from-scratch green bean casserole transforms a classic holiday side dish into something truly special. Instead of canned soup and canned green beans, this recipe uses fresh haricots verts, sautéed mushrooms, and a homemade creamy sauce made with milk, Parmesan, and fresh thyme. The result is a casserole that’s fresher, more flavorful, and more colorful than the traditional version. You can even make your own crispy onion topping! Best of all, it can be prepared a day ahead for stress-free entertaining.

Ingredients for Homemade Green Bean Casserole

For the Casserole:

• 1½ pounds fresh green beans (haricots verts or regular), trimmed and halved
• 2 tablespoons extra-virgin olive oil
• 16 ounces cremini mushrooms (or white button mushrooms), sliced
• 2 tablespoons tamari or soy sauce
• 4 garlic cloves, minced
• 2 tablespoons fresh thyme leaves
• ¼ cup all-purpose flour
• 3 cups milk (any kind—whole, 2%, oat, almond)
• 1½ teaspoons Dijon mustard
• ½ cup grated Parmesan cheese, plus more for topping
• ¼ teaspoon freshly ground black pepper
• 1½ cups French fried onions (store-bought or homemade)

For Homemade Crispy Baked Onions (Optional):

• 2 medium yellow onions, thinly sliced
• ½ cup all-purpose flour
• 1 cup panko breadcrumbs
• 2 tablespoons olive oil
• ½ teaspoon salt

Why Make Green Bean Casserole From Scratch?

Better Flavor: Fresh mushrooms and homemade cream sauce have deeper, more complex flavors than canned condensed soup.

Fresher Ingredients: Fresh green beans are crisp, vibrant, and taste infinitely better than mushy canned beans.

Control Over Ingredients: You know exactly what’s in your dish—no preservatives, additives, or excessive sodium.

Beautiful Presentation: Fresh green beans maintain their bright green color, making the casserole visually appealing.

Impressive but Easy: While it seems fancy, this recipe is straightforward and can be made ahead.

How to Make Green Bean Casserole From Scratch

Step 1: Prepare the Crispy Onions (If Making from Scratch)

Preheat oven to 375°F. Toss sliced onions with flour until coated. Add panko, olive oil, and salt, tossing to combine. Spread on two baking sheets in a single layer. Bake for 20-25 minutes, rotating pans every 10 minutes, until golden brown and crispy. Watch closely—they can burn quickly! Set aside.

Step 2: Blanch the Green Beans

Preheat oven to 400°F and lightly grease a 9×13-inch baking dish. Bring a large pot of salted water to a boil and prepare a large bowl of ice water. Drop green beans into boiling water and blanch for 4 minutes until crisp-tender and bright green. Immediately transfer to ice water to stop cooking. Drain and spread on a kitchen towel to dry thoroughly—this is important to prevent a watery casserole!

Step 3: Make the Creamy Mushroom Sauce

Heat olive oil in a large skillet over medium heat. Add sliced mushrooms and cook for 8-10 minutes until soft and browned, releasing their liquid. Stir in tamari, minced garlic, and fresh thyme. Sprinkle flour over the mushroom mixture and stir well to coat—this creates the thickening base.

Step 4: Create the Cream Sauce

Add milk and Dijon mustard to the mushroom mixture, stirring to combine. Simmer for 15-20 minutes, whisking often, until the sauce thickens to a creamy consistency. It should coat the back of a spoon. Stir in Parmesan cheese and black pepper. Taste and adjust seasoning if needed.

Step 5: Assemble the Casserole

Spread ⅓ of the mushroom sauce on the bottom of the prepared baking dish. Arrange blanched green beans evenly over the sauce. Pour the remaining sauce over the green beans, ensuring they’re evenly covered. Top with French fried onions, distributing evenly.

Step 6: Bake

Cover the casserole with aluminum foil and bake for 10 minutes. Remove foil and bake for 10 more minutes until bubbly and the onions are golden. If onions are browning too quickly, re-cover with foil. Garnish with additional Parmesan if desired. Serve hot.

Tips for the Best Green Bean Casserole

Dry the Green Beans Thoroughly: Excess water creates a watery, soupy casserole. Pat green beans completely dry after blanching.

Don’t Skip the Ice Bath: Plunging blanched beans into ice water stops the cooking process and preserves their vibrant green color.

Use Fresh Thyme: Fresh thyme has a more aromatic, earthy flavor than dried. If using dried, reduce to 2 teaspoons.

Let the Sauce Thicken: Be patient! The sauce needs the full 15-20 minutes of simmering to reach the proper creamy consistency.

Watch Homemade Onions Closely: Crispy baked onions can go from perfect to burned in minutes. Rotate pans and check frequently.

Choose Your Milk: Any milk works here—whole milk creates the richest sauce, but almond, oat, or 2% milk all work beautifully.

Make It Ahead: This casserole is perfect for advance preparation (see detailed instructions below).

Make Ahead Instructions

This green bean casserole is ideal for holiday meal prep:

Up to 1 Day Ahead:

• Blanch and dry the green beans
• Make the mushroom cream sauce completely
• Layer sauce and green beans in the casserole dish
• Cover tightly with foil and refrigerate
• If making homemade onions, store at room temperature in an airtight container

Just Before Serving:

• Remove casserole from refrigerator (no need to bring to room temperature)
• Add onion topping
• Bake according to recipe instructions, adding 5 extra minutes if needed

Recipe Variations

Vegetarian/Vegan Option: Use nutritional yeast (1:1 ratio) instead of Parmesan cheese. Some readers report excellent results!

Gluten-Free: Use gluten-free all-purpose flour and gluten-free panko breadcrumbs for the onions. The casserole itself thickens beautifully with GF flour.

Dairy-Free: Use oat milk, almond milk, or a mix of coconut milk and vegetable broth. Omit Parmesan or use nutritional yeast.

Add Bacon: Cook 4-6 strips of bacon until crispy, crumble, and mix with the onion topping for extra richness.

Frozen Green Beans: In a pinch, use frozen green beans. Skip the blanching step and add frozen beans directly to the casserole (they may release more water).

Different Mushrooms: Try shiitake, oyster, or a mix of wild mushrooms for varied flavor.

Add Almonds: Toss ¼ cup sliced almonds with the onion topping for extra crunch.

Lighter Version: Use low-fat milk and reduce Parmesan to ¼ cup.

Storage and Reheating

Refrigerator: Store leftover green bean casserole in an airtight container for up to 2 days. The onions will soften in storage.

Reheating:

• Microwave: Heat individual portions for 1-2 minutes until warmed through
• Oven: Place in a covered dish and reheat at 350°F for 15-20 minutes

Freezing: Not recommended. The cream sauce can become grainy after freezing and thawing.

Best Served Fresh: This casserole tastes best on the day it’s made, but properly stored leftovers are still delicious.

Frequently Asked Questions

Can I use frozen green beans? Yes! Skip the blanching step and add frozen beans directly. They may release more liquid, so ensure the sauce is extra thick.

What can I substitute for tamari? Regular soy sauce works perfectly. Tamari is just a gluten-free version.

Why is my sauce too thin? Continue simmering it longer. The sauce needs the full 15-20 minutes to thicken properly. Be patient and whisk often.

Can I make this completely dairy-free? Yes! Use oat milk or almond milk and replace Parmesan with nutritional yeast (start with 1 tablespoon and add more to taste).

Do I have to make the onions from scratch? No! Store-bought French fried onions work wonderfully. Homemade are just an extra-special touch.

Why do I need to dry the green beans so well? Water on the beans will dilute the sauce and make the casserole watery. Thorough drying is essential.

Can I triple this recipe for a crowd? Absolutely! Use a larger baking dish (or multiple dishes) and adjust baking time as needed.

What’s the difference between haricots verts and regular green beans? Haricots verts are thinner, more tender French green beans. Both work beautifully in this recipe.

Can I prep the components separately and assemble later? Yes! That’s the best make-ahead strategy. Store sauce, beans, and onions separately.

Troubleshooting Tips

Casserole is watery: Green beans weren’t dried thoroughly, or sauce wasn’t simmered long enough. Next time, pat beans completely dry and let sauce thicken fully.

Sauce won’t thicken: Continue simmering. It can take up to 25 minutes depending on your stove and pan. Whisk frequently.

Onions are burning: Lower oven temperature to 350°F and rotate pans more frequently. Onions need close monitoring.

Mushrooms are rubbery: Cook them longer! Mushrooms need 8-10 minutes to release their liquid and become tender.

Sauce is lumpy: Whisk vigorously after adding milk to break up flour clumps. A smooth sauce takes constant whisking.

Serving Suggestions

This homemade green bean casserole is perfect alongside:

• Roasted turkey or chicken
• Glazed ham
• Prime rib or beef tenderloin
• Mashed potatoes
• Stuffing or dressing
• Sweet potato casserole
• Cranberry sauce
• Dinner rolls

Perfect for Thanksgiving, Christmas, Easter, or any special family dinner.