Meatless Monday Challenge

Green Bean Casserole with Delicious Secret Ingredient

on October 2, 2020
last updated April 4, 2024
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This Green Bean Casserole is a Marley's Menu Tik Tok viral recipe! It utilizes a secret ingredient to boost the classic flavors of your traditional Thanksgiving favorite side dish. It also uses fresh green beans and teaches you how to keep the crisp and avoid a soggy casserole.
close up of green bean casserole with secret ingredient

Sick of the same old boring Thanksgiving Green Bean Casserole year after year? You don’t have to reinvent the wheel to spruce it up. Just add one secret ingredient for an incredible boost of flavor!

Yes, I know. I’m promising a lot. But I am so excited to introduce you to the power of the porcini in this casserole that has quickly become one of my favorite Thanksgiving recipes.

You’ve heard me rave about it before in my Truffle Mushroom Risotto recipe, and I’m doubling down with my praise.

Green Bean Casserole with Secret Ingredient being lifted on a serving spoon

Green Bean Casserole with Secret Ingredient Tips & Tricks

So What’s All This “Secret Ingredient” Talk About?

Porcini mushrooms are incredibly tasty and lend a nutty, earthy flavor to the dish. The cream of mushroom soup is delicious on it’s own, but could use a little boost when competing with other flavors in a casserole like this one.

By using this “secret ingredient” you’re just boosting the natural flavors of a classic green bean casserole, bringing it to life!

Because their growing season is short, porcini mushrooms are typically sold dried. Make sure to add them early on in the cooking process so that they have time to rehydrate.

Outside of your porcini mushroom secret ingredient, here’s everything you need:

  • Fresh green beans. Fresh beats canned any day!
  • Onion. For extra flavor.
  • Porcini mushrooms. The secret ingredient that infuses tons of umami into this dish.
  • Garlic. For more flavor.
  • Olive oil. To cook your veggies in.
  • Cream of mushroom soup. A staple in any traditional green bean casserole.
  • Cheddar cheese. A layer of cheese on top of your casserole is always a good idea.
  • Crispy fried onions. For a crispy crunchy top.
  • Salt & pepper. To amp up all the flavors.
green beans, porcini mushrooms, cheddar cheese, olive oil, garlic, onion, salt, cream of mushroom soup, black pepper

So Fresh And So Green, Green

A lot of green bean casserole recipes call for canned green beans. And I’ll admit it—this cuts out the need for boiling and reduces your total cooking time by about 15 whole minutes.

And while I’m all for shortcuts and hacks in the kitchen, the difference in taste is apparent.

Trust me, I’ve tried this casserole every which way! And taking the time to add that fresh element makes a world of a difference.

Plus, canned green beans often contain extra sodium to preserve them, making it hard to control the amount of salt in your dish.

Green tip: Food preservatives, like pesticides, are harmful to the environment. They contain toxins that are harmful to plants, animals, and soil. Homemade food with all-natural ingredients that allows you to avoid preservatives lowers your ecological footprint.

Nobody Likes A Squeaky Bean

ALWAYS boil your beans first. You need them nice and tender for a luscious casserole.

It’s best to cut off the ends and chop your green beans first. Then boil the halved beans in salted water for about 10-15 minutes until they are nice and soft.

Make sure your green beans are completely dry before adding them to your mushroom, onion, and soup mixture. Any extra moisture will negatively affect the texture of your casserole.

prepping greenbeans by chopping off ends and slicing in half

Cook Down Your Veg

Speaking of extra moisture, it’s best to avoid it. Cook the onion, garlic, green beans, and porcini mushrooms in olive oil with black pepper and a pinch of salt.

This will season the vegetables, help reduce excess moisture, and start to rehydrate the porcini mushrooms.

Cook over medium heat until the onions are translucent and there is no more liquid left in the pan. It should only take 5-10 minutes.

sauteeing chopped onion, minced garlic, salt, pepper, fresh green beans, and dried porcini mushrooms

Keep It Classic

I know classic green bean casserole can be a little bland. But the porcini mushrooms, sautéed onions, and black pepper infuse a lot of flavor without straying away from the casserole’s classic taste.

Stick to the classic flavors, just crank them up a notch! I’m confident if you follow the measurements in this recipe, you won’t be disappointed!

Once your vegetables are ready, add the cream of mushroom soup and stir until coated. Simmer for about 5 more minutes to (you guessed it!) reduce excess moisture.

pouring cream of mushroom soup over vegetables cooking in pan

You’ll Need A Baking Dish

Once you have your vegetable, spice, and soup mixture cooked and well combined, it’s time to transfer it to your baking dish!

I use a 10.5″ x 7.5″ casserole dish and find it’s perfect!

A smaller dish will give you a thicker base with fewer toppings, and a larger dish means an overall thinner casserole.

If you’re changing up the size of the casserole dish, just watch it in the oven a little more closely. This may change the cooking time a bit.

pouring cooked green bean casserole with secret ingredient components into a baking dish

The Cheddar’s Not The Big Cheese

While I’ve been known to use the words “it’s never enough cheese” often, the focus of this casserole is the green beans! Don’t overdo it with the cheddar here.

You want enough cheese to provide that ooey-gooey texture and a little extra salt, but not enough to detract from the mushroom and green bean focus. A thin layer on top will do the trick.

Sprinkle a thin layer of shredded cheddar cheese on top, leaving some areas where the green bean mixture peeps through.

adding layer of cheddar cheese on top of green bean casserole

When It Comes To The Crunch…

…there is just nothin’ better than those crispy fried onions. To me, you can’t call it Thanksgiving without these flavorful little crunchies.

They make the perfect topping for that crispy texture to finish off this creamy, cheesy delight.

You’ll know your green bean casserole is done when the crispy fried onion topping is just starting to brown.

super close up of green bean casserole on a serving spoon

How to Properly Store and Reheat Cheesy Green Beans with Cream of Mushroom Soup

In a sealed container in the refrigerator, this elevated green bean casserole will last up to 5 days. It can also be frozen for up to 6 months.

The best way to reheat this casserole with green beans is in the oven. Preheat the oven to 350°F and reheat on the top rack for about 15 minutes per serving until heated through.

You can cover the casserole with aluminum foil to help it heat up more quickly but remove the foil for the last couple of minutes to get the onions on top crispy again.

You can safely microwave it, but the crispy onions on top will likely lose their crunch.

Green tip: Of the billions of tons of food wasted annually, 50% of food waste happens at home. Reduce your contribution to food waste by properly storing and consuming leftovers.

Green Bean Casserole Frequently Asked Questions

How do you make green bean casserole not runny?

The technique to avoiding a runny casserole in this recipe is pre-cooking the green beans, onions, garlic, and porcini mushrooms to reduce the amount of liquid.

What can I add to green beans for flavor?

Adding porcini mushrooms to green bean casserole is a great way to infuse extra umami and deeper flavor.

Want to sharpen your kitchen skills?

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Why You Should Make this Green Bean Casserole With Secret Ingredient

  • It’s classic. It’s not Thanksgiving without this classic.
  • It’s flavorful. All the classic flavors of a green bean casserole, but the secret ingredient just amps up the flavor.
  • It’s the perfect side dish. There are not many things that you can’t serve this with!

If you’re loving this Green Bean Casserole with Secret Ingredient and are on the hunt for other Thanksgiving side dish ideas, check out these Garlic and Feta Mashed Potatoes and Sweet and Salty Brussels Sprouts.

Whether you are enjoying this casserole on Thanksgiving, Friendsgiving, or just a random Tuesday night, I am thankful that you are trying my recipe! It’s always a good time to say thank you!

close up of green bean casserole with secret ingredient

Green Bean Casserole with Secret Ingredient

5 from 3 votes
Marley Goldin
This Green Bean Casserole utilizes a secret ingredient to boost the natural flavors of your traditional Thanksgiving favorite for a whole new dinner sides experience.
Prep Time 25 minutes
Cook Time 35 minutes
Total Time 1 hour
Servings 8 servings



  • 1 pound fresh green beans (halved)
  • 1 large yellow onion
  • 3 cloves garlic
  • ¼ cup dried porcini mushrooms
  • 2 tablespoons olive oil
  • ½ teaspoon black pepper
  • 1 pinch of salt
  • 21 ounces cream of mushroom soup (21 oz usually = 2 cans)
  • 4 ounces cheddar cheese
  • 2.8 ounces crispy fried onions


  • Preheat your oven to 350°F and bring 10 cups of water to a boil in a large pot.
  • Trim the ends off your fresh green beans and cut them in half. Boil them until tender—about 10-15 minutes.
  • Dice your onions and mince your garlic.
  • Once your green beans are tender, strain them and dry them off with a kitchen towel.
  • Add cooked green beans, onions, garlic, and porcini mushrooms to a frying pan with salt, pepper, and olive oil over medium heat until onions are transparent.
  • Add cream of mushroom soup and mix well. Simmer on low for about 5 minutes to reduce excess moisture.
  • Transfer your green bean mixture to a 10.5" x 7.5" oven-safe casserole dish. Top with a thin layer of cheese, and finalize with a layer of crispy fried onions.
  • Bake for 30-35 minutes until cheese is nice and melted and crispy onions are starting to brown.

Pro Tips

  • Always, always boil your green beans before adding them to your casserole. Squeaky green beans are not a welcoming bite!
  • Add your porcini early so they have time to rehydrate.
  • This dish is a classic holiday recipe. For more like this, check out my comprehensive list of the best Thanksgiving recipes.
Course Sides
Cuisine American
Diet Vegetarian
Keyword Easy, Fall, Green Bean Casserole, Porcini Mushrooms, Thanksgiving Side Dishes
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