Green Bean Casserole from Scratch
A classic American green bean casserole made entirely from scratch: crisp-tender green beans, a creamy mushroom sauce built on a simple roux, and crunchy homemade fried onions. Familiar, comforting, and noticeably fresher than the shortcut version.
Green bean casserole became a holiday staple because it’s simple, savory, and reliably crowd-pleasing. Making it from scratch is a great lesson in classic American technique: a roux-thickened sauce, properly seasoned vegetables, and a crunchy topping for contrast. Once you taste the depth from real mushrooms and onions, you’ll understand why this version earns its place on the table.
Total Time
1 hr 5 min
Prep Time
30 min
Cook Time
35 min
Servings
8
Ingredients
Green Beans
- •1 1/2 lb fresh green beans, trimmed and cut into 2-inch pieces
- •1 1/2 tsp kosher salt, plus more for blanching water
Homemade Fried Onions
- •2 large yellow onions, thinly sliced
- •1 cup all-purpose flour
- •1 tsp kosher salt
- •1/2 tsp black pepper
- •1/2 tsp garlic powder (optional)
- •Neutral oil for frying (vegetable/canola), about 2–3 cups
Mushroom Cream Sauce
- •4 tbsp unsalted butter
- •12 oz cremini (baby bella) mushrooms, sliced
- •1 small yellow onion or 2 shallots, finely diced
- •2 cloves garlic, minced
- •1/4 cup all-purpose flour
- •1 1/2 cups low-sodium chicken stock (or vegetable stock)
- •1 cup whole milk (or half-and-half for richer)
- •1 tsp Dijon mustard
- •1 tsp Worcestershire sauce
- •1/2 tsp freshly ground black pepper
- •Pinch of cayenne or smoked paprika (optional)
Finish & Bake
- •1/2 cup grated Parmesan (optional but excellent)
- •1 tbsp chopped fresh parsley (optional, for serving)
Instructions
- 1
Heat oven to 375°F. Lightly butter a 9x13-inch baking dish (or a 3-quart casserole).
- 2
Blanch the green beans: bring a large pot of well-salted water to a boil. Add green beans and cook 3–4 minutes until bright green and crisp-tender. Drain and immediately rinse under cold water (or shock in ice water) to stop cooking; drain well and set aside.
- 3
Make the fried onions: in a large bowl, toss sliced onions with flour, salt, pepper, and garlic powder (if using) until well coated. Heat 1 inch of neutral oil in a deep skillet or Dutch oven to 350°F. Fry onions in small batches, stirring and separating rings, until golden brown (about 2–4 minutes per batch). Transfer to a paper towel–lined plate and lightly salt while hot. Set aside.
- 4
Build the mushroom base: melt butter in a large skillet over medium-high heat. Add mushrooms and cook 6–8 minutes, stirring occasionally, until they release moisture and begin to brown. Add diced onion/shallot and cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds.
- 5
Thicken the sauce: sprinkle flour over the mushroom mixture and stir constantly for 1 minute to cook off the raw flour. Slowly whisk in stock, scraping up browned bits. Whisk in milk. Bring to a gentle simmer and cook 3–5 minutes, stirring, until thick enough to coat a spoon.
- 6
Season: stir in Dijon and Worcestershire. Add kosher salt (start with 1/2 tsp; adjust to taste), black pepper, and optional cayenne/smoked paprika. Taste and adjust—this casserole should be well-seasoned before baking.
- 7
Combine: add blanched green beans to the sauce and fold to coat. If using Parmesan, stir in half now.
- 8
Assemble: spread the mixture into the prepared baking dish. Top with half of the fried onions (and remaining Parmesan, if using).
- 9
Bake 20 minutes, until bubbling around the edges. Remove from oven, top with remaining fried onions, and bake 5–8 minutes more until the onions are deeply golden and the casserole is hot throughout.
- 10
Rest 5 minutes before serving. Finish with parsley if desired.
Nutrition Facts
Per serving
* Percent Daily Values are based on a 2,000 calorie diet.
Nutrition calculated automatically from ingredients.