Classic green bean casserole in a white baking dish topped with crispy fried onion rings, a serving spoon lifting out the creamy mushroom sauce

From-Scratch Green Bean Casserole with Homemade Fried Onions

Published by Fork Around & Find Out Kitchen — presented in the Lila editorial voice. Editorial standards

Quick Answer

Blanch 2½ pounds fresh green beans, fold them into a from-scratch sherry cream mushroom sauce, and spread in a 9x13 dish — this part can be covered and refrigerated up to 24 hours ahead. Fry your own onion rings in a buttermilk-and-flour dredge, bake the casserole at 350°F until bubbling, then top with the fried onions for a final 8 to 10 minutes so they go on crisp.

Jump to Recipe

Green bean casserole has spent decades being defended mostly on nostalgia, which is a lot of pressure to put on a can of soup. This from-scratch version keeps the part people actually love—the creamy mushroom sauce, tender green beans, and crunchy onion topping—but makes each one taste like itself. Fresh beans are blanched until bright and just tender, cremini mushrooms are browned until their moisture cooks off, and a little dry sherry gets scraped into the pan before stock and cream turn those browned bits into the sauce.

The onions get their own treatment: a buttermilk soak, seasoned flour, and a quick fry at 350°F until crisp and deeply golden. They go on near the end so they stay crunchy instead of absorbing steam for half an hour and emerging with the structural integrity of wet receipts. Better yet, the bean-and-mushroom portion can be assembled a day ahead, leaving only baking and the onion finish for the holiday. Same familiar casserole, just with considerably more evidence that vegetables were involved.

Prep35 minutes

Cook55 minutes

Total1 hr 30 min

Serves10 to 12 servings

DifficultyMedium

Ingredients

Servings

Green Beans and Sauce

2½ pounds fresh green beans, trimmed and cut into 2-inch pieces
2 tablespoons Diamond Crystal kosher salt, for the blanching water
4 tablespoons unsalted butter
12 ounces cremini mushrooms, thinly sliced
1 small yellow onion, finely diced
3 garlic cloves, minced
¼ cup all-purpose flour
2 tablespoons dry sherry
1½ cups unsalted or low-sodium chicken or turkey stock
1 cup heavy cream
¾ teaspoon kosher salt, plus more to taste
½ teaspoon freshly ground black pepper

Homemade Crispy Onions

2 large yellow onions, sliced into thin rings, about ⅛ inch thick
2 cups buttermilk
1½ cups all-purpose flour, for dredging
1 teaspoon kosher salt, for the dredge
½ teaspoon freshly ground black pepper, for the dredge
½ teaspoon garlic powder
4 cups neutral oil, for frying
Additional kosher salt, for seasoning the fried onions

Instructions

1Soak the onions for the fried topping. Separate the onion rings and submerge them in the 2 cups of buttermilk. Let them soak at least 30 minutes at room temperature, or cover and refrigerate up to overnight. This can happen while you handle the rest of the prep below.
2Blanch the green beans. Bring a large pot of water to a boil and add the 2 tablespoons kosher salt. Add the green beans and cook 5 to 6 minutes, until bright green and just tender with a slight bite left. Drain immediately and plunge into a bowl of ice water to stop the cooking. Drain again and pat completely dry.
3Build the mushroom cream sauce. Melt the 4 tablespoons butter in a large skillet over medium-high heat. Add the mushrooms and diced onion and cook 8 to 10 minutes, stirring occasionally, until the mushrooms are deeply browned and the liquid they release has evaporated. Add the garlic and cook 30 seconds until fragrant. Sprinkle in the ¼ cup flour and cook, stirring, for 2 minutes. Pour in the sherry and scrape up any browned bits, then whisk in the stock gradually until smooth. Add the cream, bring to a simmer, and cook 4 to 5 minutes until the sauce coats the back of a spoon. Season with the ¾ teaspoon salt and ½ teaspoon pepper.
4Combine and hold, or bake now. Butter a 9x13-inch baking dish. Fold the blanched green beans into the mushroom sauce and spread into the dish. At this point you can cover and refrigerate up to 24 hours, or continue straight to baking.
5Fry the onions. Drain the soaked onion rings. Whisk together the 1½ cups flour, 1 teaspoon salt, ½ teaspoon pepper, and garlic powder in a shallow dish. Heat the 4 cups oil in a heavy pot to 350°F. Working in small batches, dredge the onion rings in the seasoned flour, shaking off the excess, and fry 2 to 3 minutes until deep golden brown. Transfer to a wire rack and salt immediately while still hot. Repeat with the remaining onions.
6Bake the casserole. Heat the oven to 350°F. Bake the casserole uncovered 25 to 30 minutes if freshly assembled, or 35 to 40 minutes if starting cold from the refrigerator, until the sauce is bubbling at the edges.
7Top and finish baking. Scatter the fried onions evenly over the top and return to the oven for 8 to 10 minutes, until the onions are re-crisped and the edges of the casserole are deeply bubbling.
8Rest briefly, then serve. Let the casserole stand 5 to 10 minutes before serving. This gives the sauce a moment to settle so it holds together on the spoon instead of running.

Nutrition Information

Estimated per serving: 1 serving (calculated using 11 servings, the midpoint of the stated 10–12 range).

330Calories

8 gProtein

29 gCarbohydrates

21 gTotal Fat

9 gSaturated Fat

4 gFiber

8 gTotal Sugars

1840 mgSodium

43 mgCholesterol

Estimated from the ingredients and quantities in this recipe using standard food-composition values. The calculation uses the midpoint of the stated yield range. Brand choices, trimming, cooking loss, optional ingredients, and actual portion size can change the numbers. How we calculate nutrition estimates.

Pro Tips

Salt the onions the second they leave the oil. Salt only sticks to hot, wet-with-oil surfaces. Wait even two minutes and it slides right off instead of clinging, so have your salt ready at the fryer, not across the kitchen.
Dry the beans completely after blanching. Wet beans thin out the sauce and dilute the flavor. Pat them dry on a clean towel before they go anywhere near the mushroom cream.
Brown the mushrooms, don't just cook them. Mushrooms release a lot of water first and look done long before they are. Keep them moving until that water is fully gone and they start to actually color — that's where the flavor lives.
Fry in small batches. Crowding the pot drops the oil temperature fast, and the onions steam instead of crisp. Give them room and check the oil temperature between batches.
Onions go on last, always. Add them at the very end of baking, never underneath a full second bake. Buried onions turn soft; onions added for the final 8 to 10 minutes stay genuinely crisp.

Substitutions

cremini mushrooms → white button mushrooms Milder flavor, same technique. Brown them the same way — button mushrooms release even more water, so give them a few extra minutes.

dry sherry → dry white wine, or a splash of stock plus 1 teaspoon lemon juice You're after acidity to deglaze the pan and cut the richness. Any of the three does the job.

heavy cream → half-and-half Lighter but noticeably less rich. The sauce will need a minute or two longer to thicken to the same consistency.

frying your own onions → store-bought crispy fried onions Use about 2½ cups and skip the buttermilk soak and dredge entirely. Our quicker green bean casserole is built around exactly this shortcut.

fresh green beans → frozen green beans, thawed and patted dry Skip the blanching step entirely, since frozen beans are already partially cooked. Go straight into the sauce.

Storage Instructions

Refrigerate leftovers in an airtight container for up to 4 days. The onions will soften once they hit the sauce, which is normal — there's no version of leftovers where they stay crisp. Reheat covered at 350°F for about 15 minutes.

Make Ahead

This casserole is built for make-ahead. Assemble the beans and sauce in the baking dish up to 24 hours before, cover, and refrigerate. Fry the onions up to 2 days ahead and store them at room temperature, never in the fridge. On Thanksgiving Day you're only baking and scattering onions on top.

Freezer

Freeze the assembled but unbaked beans and sauce, without the onions, for up to 2 months. Thaw overnight in the refrigerator, then bake and top with freshly fried onions. Do not freeze the fried onions themselves; they lose their crispness completely on thawing.

Frequently Asked Questions

What makes this different from a regular green bean casserole?

Two things: the crispy onions are fried from scratch instead of coming from a can, and the whole dish is built to assemble a day ahead. If you want the same fresh-bean, scratch-sauce idea with store-bought fried onions and less lead time, our other green bean casserole is the faster route to the same flavor.

Can I use canned or frozen green beans instead of fresh?

Frozen works reasonably well; thaw and pat them dry, then skip the blanching step and go straight into the sauce, since they are already partially cooked. Canned green beans are already fully soft and will turn to mush under a second bake, so they are not a good match for this particular technique.

Can I make the fried onions ahead of time?

Yes, up to 2 days ahead. Let them cool completely, then store in an airtight container at room temperature with a paper towel to absorb any stray moisture. Do not refrigerate them, since the cold air will make them go soft and chewy instead of staying crisp.

Why blanch the green beans first?

Blanching partially cooks the beans and locks in their bright green color, then the ice bath stops the cooking so they keep a slight bite. Skip it and the beans finish the bake either undercooked and squeaky or, more likely, gray and completely soft, since a casserole bake alone is not enough heat and time to cook raw beans through evenly.

Can I assemble this the day before Thanksgiving?

Yes, and it is built specifically for that. Assemble the beans and sauce in the baking dish, cover, and refrigerate up to 24 hours ahead. Fry the onions separately and store them at room temperature. Bake the casserole uncovered, then scatter the onions on top for the final 8 to 10 minutes so they go on crisp.

My sauce is too thin. What happened?

Most likely the roux did not cook long enough before the liquid went in, or the sauce did not simmer long enough afterward. Cook the flour and butter for a full 2 minutes until it smells nutty, then simmer the finished sauce until it coats a spoon before it ever touches the green beans.