Recipes » Side Dishes » Vegetables

Green Bean Casserole

Yumna Jawad

Updated Aug 25, 2026

4.90 from 65 votes

Green bean casserole from scratch with frozen green beans, homemade mushroom sauce, and crispy baked onions instead of canned soup.

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Prep Time 35 minutes mins

Servings 8 servings

Comments

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The first time I had a green bean casserole from scratch was long after the canned version I grew up with. Back then, it was very heavy, with canned soup and crispy onions, also from a can, and while it was okay, it wasn’t exactly fresh. Now I make my own green bean casserole from scratch with fresh mushrooms, a simple homemade cream of mushroom soup, and a homemade crispy onion topping. It’s soo good!

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Recipe testing notes

For the past 10 years, I’ve tested every recipe before sharing it with you! These notes give you a peek into the process of developing this green bean casserole recipe.

The homemade mushroom soup was the whole reason I wanted to develop this. I cook the mushrooms down until they’ve browned and released their liquid, because that’s where all the deep flavor comes from, and rushing that step left the sauce watery and bland.

The baked onions took the most trial and error. Slicing them really thin, a mandoline helps here, is what lets them crisp up instead of going leathery. But the bigger lesson was watching them like a hawk at the end, because they go from golden to burnt in a matter of a minute or two. Spreading them in a single layer so they’re not crowded helped them crisp evenly too.

Happy Cooking!
– Yumna

Green Bean Casserole Ingredients

• Green beans: I use frozen cut green beans because they’re convenient and you don’t need to thaw them first. If you’d rather make a fresh green bean casserole, blanch 2 pounds of trimmed fresh green beans for 4–5 minutes, then drain well before assembling. Here’s a quick tutorial on how to blanch vegetables!
• Mushroom sauce: Button mushrooms, onion, minced garlic, olive oil, milk, cornstarch, water, reduced-sodium soy sauce, salt, and black pepper create the sauce. Try cremini, shiitake, or oyster mushrooms, or a mix! Read my tips on how to slice mushrooms and how to slice an onion evenly so they brown instead of steaming. I use 2% milk to keep things lighter, but you can use whole milk, half and half, or heavy cream if you like. To make this dish vegan, use an unsweetened plant-based milk like oat, almond, or soy. To make it gluten-free, use tamari or coconut aminos in place of soy sauce.
• Crispy onion topping: Onion, all-purpose flour, panko breadcrumbs, olive oil, salt, and black pepper. Slice the onion as evenly as possible so everything crisps at the same rate. A mandoline makes this much easier if you have one!

How to Make Green Bean Casserole

These step-by-step photos show how I make green bean casserole from scratch. For the full ingredient list and detailed instructions, scroll down to the recipe card below, or jump straight to the → Green Bean Casserole Recipe

1. Prep the onion topping

Coat the sliced onions with the flour, panko, seasonings, and olive oil, then spread them into an even layer on a parchment-lined baking sheet.

2. Bake until crispy

Bake the onions, tossing once halfway through, until they’re golden brown and crisp. Keep an eye on them near the end so they don’t burn.

3. Brown the mushrooms

Cook the mushrooms in olive oil until they’ve released their moisture and are nicely browned.

4. Add the onion and garlic

Stir in the onion and garlic, then continue cooking until the onion softens and the garlic smells fragrant.

5. Add the milk

Pour in the milk and bring everything to a gentle simmer while stirring occasionally.

6. Finish mushroom soup

Make the cornstarch slurry before adding it to the skillet so it blends in smoothly without lumps. Whisk in the cornstarch slurry until the sauce thickens, then stir in the soy sauce, salt, and pepper.

7. Add the green beans

Spread the frozen green beans evenly in a baking dish.

8. Coat with mushroom sauce

Pour the mushroom sauce over the green beans and stir until everything is evenly coated.

9. Add crispy onion topping

Scatter the baked onions over the top so the casserole is evenly covered.

10. Bake the casserole

Bake until the filling is bubbling around the edges and the onion topping is deeply golden.

I have made the Campbell soup green bean casserole. My son, who is in his 20s, hated it. I printed your recipe to make. I decided I was just going to skip it and make a quicker recipe. He saw your recipe and wanted to make it. It was delicious, and we ate all the leftovers. Everyone loved this green bean casserole. Love your recipes ❤️❤️ – Lori

Full From Scratch Green Bean Casserole Recipe

Green Bean Casserole Recipe

Author: Yumna Jawad

4.90 from 65 votes

Green bean casserole made from scratch with a homemade mushroom sauce and baked crispy onions. No canned soup!

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Prep Time35 minutes mins

Cook Time25 minutes mins

Total Time1 hour hr

Servings8 servings

Video

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Ingredients

  

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For the Baked Crispy Onion Topping:

• ▢ 1 large onion very thinly sliced (mandoline recommended)
• ▢ ¼ cup all-purpose flour
• ▢ ½ cup panko breadcrumbs
• ▢ ½ teaspoon salt
• ▢ ¼ teaspoon black pepper
• ▢ 2 tablespoons olive oil

For the Mushroom Sauce and Green Beans:

• ▢ 1 tablespoon olive oil
• ▢ 1 pound mushrooms sliced
• ▢ 1 large onion thinly sliced
• ▢ 3 garlic cloves minced
• ▢ 2 cups 2% milk
• ▢ 3 tablespoons cornstarch
• ▢ 2 tablespoons water
• ▢ 2 teaspoons soy sauce
• ▢ ½ teaspoon salt
• ▢ ½ teaspoon black pepper
• ▢ 2 pounds frozen cut green beans
• ▢ Cooking spray

Instructions

Make the Baked Crispy Onions

• Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
• In a large bowl, toss onions with flour, panko, salt, and pepper. Drizzle olive oil over the mixture and toss again until evenly coated.
• Spread onions out in a single layer on the baking sheet and bake for 15–20 minutes, tossing halfway, until golden and crisp. Watch closely near the end to prevent burning.

Make the Mushroom Sauce

• In a large skillet over medium-high heat, add olive oil and mushrooms. Cook until browned, softened and releasing liquid, about 10 minutes.
• Reduce heat to medium, add the onion and garlic, and cook until onions are translucent, about 5 minutes more.
• Add milk and bring to a low simmer. In a small bowl, stir together cornstarch and water, then add to the skillet. Stir frequently until thickened. Add the soy sauce, salt and pepper and stir again to combine.

Assemble and Bake

• Place the frozen green beans in a 9×13 baking dish. Pour the mushroom mixture over the green beans and stir to coat. Top evenly with the baked crispy onions.
• Bake until the casserole is bubbling and the topping is golden, 10–15 minutes. Serve warm.

Notes

Note: This recipe was updated in September 2025 to use a homemade crispy onion topping instead of breadcrumbs (as shown in the recipe video).

My Top Tip: Bake the onions until they’re fully crisp before adding them to the casserole. They soften slightly during the final bake, so starting with crispy onions gives the best texture.

Storage: Once your green bean casserole cools down to room temperature, transfer any leftovers to an airtight container or cover the baking dish tightly with foil or plastic wrap. Refrigerate it within 2 hours of baking. The casserole will last 3–4 days in the fridge. To reheat the casserole, warm individual portions in the microwave or place the whole dish in a 350°F oven until warmed through.

Freezing: Make sure to use a freezer-safe baking dish and, after cooling, wrap the dish in a few layers of foil to prevent freezer burn. It’ll last 3 months in the freezer. Thaw the casserole overnight in the fridge before reheating.

Nutrition

Serving: 1cup, Calories: 182kcal, Carbohydrates: 26g, Protein: 7g, Fat: 7g, Saturated Fat: 2g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 4g, Trans Fat: 0.1g, Cholesterol: 5mg, Sodium: 400mg, Potassium: 651mg, Fiber: 4g, Sugar: 10g, Vitamin A: 845IU, Vitamin C: 17mg, Calcium: 142mg, Iron: 2mg

Nutrition information provided is an estimate. It will vary based on cooking method and specific ingredients used.

Did You Make This Recipe?

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Recipe Variations

• Add cheese: Stir 1 cup shredded Gruyère, Swiss, or white cheddar into the mushroom sauce before assembling.
• Make it extra herby: Stir in 1 tablespoon chopped fresh thyme or rosemary with the mushrooms.
• Add toasted nuts: Sprinkle ¼ cup chopped toasted pecans or toasted almonds over the green bean casserole after baking for extra crunch.

“I had never made green bean casserole before, and neither had my family. I made this for them and it was such a big hit. We all loved it! I was glad it was easy to make!!” – Gabriela

Recipe Tips

1. Make a smoother mushroom sauce. After cooking, you could blend the sauce or dice the mushrooms instead of slicing them.
2. Check the crispy onions often. Because they’re sliced so thin, they can burn super fast! I recommend checking them every minute toward the end of cooking.
3. Don’t thaw the green beans first. If you do, this can make them taste watery and make the casserole soupy.

Serving Ideas

• Thanksgiving turkey: This green bean casserole is the perfect Thanksgiving side. Serve it with my dry brined turkey breast, whole roasted turkey, or air fryer turkey breast.
• Thanksgiving sides: The sides are the real stars of Thanksgiving! The green bean casserole tastes great with classics like Thanksgiving stuffing, roasted garlic mashed potatoes, and baked macaroni and cheese.
• Bread: Don’t skip the bread! My homemade dinner rolls, biscuits, and garlic cheese bread are all great for scooping up the extra mushroom sauce.

Troubleshooting

More Veggie Side Recipes

• Green Beans with Almonds
• Roasted Parmesan Potatoes
• Baked Butternut Squash Fries
• Pan Roasted Brussel Sprouts
• Roasted Cabbage
• Sweet Potato Bites
• Cheesy Oven Roasted Asparagus