Green Bean Casserole
This Green Bean Casserole recipe is made completely from scratch with fresh green beans and real ingredients! Tender green beans are blanketed in a homemade creamy mushroom sauce spiked with cheese and sour cream then topped with crunchy homemade fried onions. The resulting easy Green Casserole recipe is irresistibly creamy, cheesy, comforting perfection that is guaranteed to become your go-to from now on! I’ve also included helpful tips and tricks, recipe variations and how to make this Green Bean Casserole days ahead of time – just add the onions then bake!
Servings Prep Time
10-14 servings 45minutes
Cook Time
Servings Prep Time
10-14 servings 45minutes
Cook Time
up close of a spoonful of easy green bean casserole
  • 1 yellow onionthinly sliced
  • 1 red onionthinly sliced
  • 2 1/2cups buttermilk(see DIY below)
  • 1 1/2cups all-purpose flour
  • 1cup panko breadcrumbs
  • 1/2tsp EACH salt and pepper
  • vegetable or canola oil for frying
  • 1 3/4pounds (28 oz) green beanstrimmed and cut in half
  • 3tablespoons unsalted butter
  • 2tablespoons olive oil
  • 12oz. cremini mushroomssliced ¼” thick
  • 4 garlic clovesminced
  • 1teaspoon salt
  • 1/4cup all-purpose flour
  • 3cups low sodium chicken broth
  • 1/2cup heavy cream
  • 1 1/2teaspoons Dijon mustard
  • 1 1/2teaspoons Worcestershire sauce
  • 1tsp EACH dried thyme, dried parsley
  • 1/2teaspoon pepper
  • 1/4tsp EACH dried oregano, nutmeg
  • 1/2cup freshly grated cheddar cheese
  • 1/4cup freshly grated Parmesan cheese
  • 1/2cup sour cream
  1. Add onions to a shallow baking dish and pour buttermilk over top. Press the onions down so they’re submerged as much as possible. Let them soak at room temperature for an hour, stirring and pushing down occasionally. Cover and refrigerate if soaking longer.
  2. When ready to fry onions, fill a Dutch oven or deep heavy duty pot with approximately 2 inches of oil. Heat to 375 degrees F.
  3. While heating, combine flour, panko, salt and pepper in a large bowl; set aside. Line a large baking sheet with paper towels; set aside.
  4. Test the oil with a small pinch of panko; if it bubbles and fries, then it is hot enough. Using tongs, transfer a handful of onions from the buttermilk to the flour/panko mixture. Toss to combine, shake off any excess flour, then carefully transfer to the hot oil.
  5. Fry onions until lightly golden brown (just 1-2 minutes), watch closely! – they will continue to darken when baked. Remove fried onions with a heat-proof slotted spoon or tongs to paper towels. Repeat with the remaining onion slices.
  1. Bring a large pot of water to a boil and stir in two tablespoon salt. Add the green beans and blanch 5 minutes (start timing as soon as you add the beans). Meanwhile, prepare a large bowl of ice water to transfer the greens to. Using a slotted spoon, transfer beans to ice water to stop cooking. Drain the beans and set aside.
  2. Melt 3 tablespoons butter with 2 tablespoons olive oil over medium heat in a Dutch oven or large pot. Add mushrooms and cook until nicely browned and starting to soften, 3-5 minutes. Season with 1 teaspoon salt and add garlic; sauté 30 seconds.
  3. Whisk in flour then cook, while stirring for 1 minute. Turn heat to low then gradually whisk in chicken broth and heavy cream followed by Dijon, Worcestershire sauce and all spices/seasonings.
  4. Bring sauce to a boil, whisking constantly then reduce heat to a simmer, whisking often until thickened, about 6-8 minutes.
  5. Remove skillet from heat and whisk in cheddar until melted followed by Parmesan cheese until melted. Whisk in sour cream until blended.
  6. Pat green beans dry then add to sauce; stir to combine. Stir in 1 ½ cups fried onions. Stir in additional broth if needed to thin.
  7. Transfer green beans to a lightly greased 9×13 baking dish. Top with desired amount of onions. Bake at 350 degrees F for 15-20 minutes or until hot and bubbly.
Recipe Notes


Add 2 1/2 tablespoons lemon juice or white vinegar to a 3 cup+ measuring cup.  Add enough milk to equal 2 1/2 cups.  Give it a stir then wait 10-15 minutes for it to curdle, then give it another stir before using.   If you only have 1% milk, then add a splash of heavy cream before filling the rest of the measuring cup with milk.


  • Pre-cut green beans.  To save time, you can purchase pre-cut, pre-washed green beans.  They are easy to find in 2-pound bags.  I usually go for the bagged organic green beans because they seem to be thinner.  You will still have to chop the beans in half, but the ends will be trimmed.
  • Dry green bean.  Make sure to pat green beans very dry so they don’t introduce additional moisture to he mushrooms sauce and make it runny.
  • Brown mushrooms.  Cook the mushrooms until they are lightly brown and release most of their moisture, this can take up to 5 minutes, so be patient. Also don’t add the salt until the very end as per instructions, because salt will make the mushrooms retain water and inhibits the browning process.
  • Cook flour long enough.  After you sprinkle the flour over the mushrooms, make sure you cook for a full 1-2 minutes until that nutty smell.  This indicates the flour is cooked.
  • Turn heat to low: Add the broth and heavy cream over low heat and keep stirring to prevent lumps.
  • Thicken but not too thick.  The sauce will require up to 8 minutes to thicken – so be patient and simmer on but don’t thicken the sauce too much because it will continue to thicken with the addition of the cheeses and the sour cream.   The sauce is the right consistency when you can draw a path across the back of the spoon.
  • Thin sauce if needed.  The homemade cream of mushroom sauce can become too thick if simmered at too high of heat or for too long.  But don’t worry, it’s SO easy to fix!  Simply stir in a little chicken broth until it reaches desired consistency.


  • Thinly slice onions.  Thinly sliced onions ensure the ideal proportions of onions to coating to casserole.   To shortcut this process, use a mandolin slicer if you have one.
  • Slice onions ahead of time.  You can slice the onions a day ahead of time and refrigerate in an airtight bag if you aren’t ready to fry right away.  This will cut down on the onion prep significantly.
  • Oil temperature.  You want your oil to be about 375 degrees F which means it will be shimmering but not smoking.  If your oil starts to smoke, lower the heat and give it some time to cool before adding the onions.  Once you’ve tested that your oil is hot enough with some panko, you still want to make sure it’s not too hot, so it’s always a good idea to do a small test batch first.
  • Stir onions. Once you add the onions to the hot oil, give them a stir to break up any of the onions that may be sticking together.
  • Watch closely.  The onions don’t take long at all to fry up – just a minute or two per batch, so make sure to watch closely.  To check for doneness, use your slotted spoon and lift a few out of the pot because it can be hard to see their true color in the oil.
  • Don’t over-fry.  The onions should be lightly golden and not dark golden when you remove them from the oil because they are also going in the oven for 15 minutes in which they will continue to cook.
  • If you overcook onions then don’t add them to the casserole while it bakes for the full time.  Instead, add them to the casserole the last few minutes of baking just to warm through.


This easy Green Bean Casserole is a great make ahead side!   You can make the fried onions and the green beans with sauce then just combine and bake when ready.  Here’s how:

  • Onions:  Fry onions according to directions.  Let onions cool COMPLETELY before transferring to an airtight container. Store onions at ROOM TEMPERATURE for up to three days.
  • Green beans:  Prepare green bean casserole according to directions up to the point of adding the onions – keep onions separate.  Tightly cover baking dish and refrigerate up to 48 hours.
  • Bake.  When ready to bake, stir in 1-2 tablespoons milk into the green beans and give them a stir, COVER with foil, and bake for 15 minutes.  Remove foil, add onions to the top of the green beans and bake, UNCOVERED for an additional 15 minutes or until the Green Bean Casserole is completely warmed through.


Green Bean Casserole should be stored in an airtight container in the refrigerator.  When stored properly, it is good for up to 5 days, just keep in mind that the onions won’t be as crispy when reheated.