Campbell's String Bean Casserole Recipe: Cheesy, Creamy One-Pan Classic

This Campbell's string bean casserole recipe brings back the comforting flavors of childhood dinners—creamy, cheesy, and packed with tender green beans in one easy pan. 💛 I first made it during a particularly busy week when I needed a meal that required minimal effort but maximum satisfaction.

The secret lies in the perfect balance of Campbell's cream of mushroom soup, cheddar cheese, and crispy fried onions that add a satisfying crunch.

The beauty of this classic dish is its simplicity—just a handful of ingredients that come together in a single baking dish. You'll need fresh green beans (or frozen if preferred), a can of Campbell's cream of mushroom soup, shredded cheddar cheese, and a few pantry staples.

The recipe delivers that nostalgic, homey flavor without requiring any special skills or equipment. It's the kind of meal that tastes even better the next day when the flavors have had time to meld.

By the time it emerges from the oven, you'll have a bubbling, golden casserole with tender green beans swimming in a rich, creamy sauce and topped with melted cheese and crispy onions.

This is the kind of dish that disappears quickly, so make sure to have plenty on hand—it's perfect for family dinners, potlucks, or when you're craving that classic comfort food feeling. The best part? Leftovers reheat beautifully, making it an ideal meal prep option.

For an extra touch of flavor, consider adding cooked bacon or a sprinkle of black pepper before baking. Serve with crusty bread or a simple side salad to round out the meal. Let's get started on this timeless classic that never fails to impress.

Ingredients for campbell's string bean casserole

Nostalgic comfort in one pan—just these 11 ingredients transform into cheesy, creamy string bean heaven.

The green beans are the star, so pick fresh ones with crisp stems—they should snap like a twig. Trader Joe's or Whole Foods usually have the best quality, but the regular grocery store works too. If you're short on time, frozen green beans (thawed and drained) work perfectly—just don't overcook them. The Campbell's cream of mushroom soup is non-negotiable here—it's the secret to that nostalgic, creamy texture. Grab the condensed version for simplicity, but if you're feeling fancy, you can make your own mushroom sauce base. The cheddar? Sharp is key—it adds that tangy bite that makes this dish sing. I always buy a block and grate it myself—pre-shredded gets clumpy and lacks flavor.

No Campbell's cream of mushroom soup? Substitute with a mix of cream of celery and cream of chicken soups—it's not the same, but close. Short on cheddar? Add a sprinkle of Parmesan for extra umami. The fried onions can be swapped for crushed potato chips (trust me, it works) if you're in a pinch. The milk and butter combo is what makes the sauce rich and velvety—don't skip it! For the bacon lovers, cook it crispy and crumble it over the top before baking. No bacon? A dash of smoked paprika adds depth without the extra fat. The flour is just for thickening, but if you're gluten-free, cornstarch works in a 1:1 ratio.

This casserole tastes even better the next day, so make it ahead and refrigerate—it reheats beautifully. Leftovers keep for 4-5 days in the fridge, and it freezes like a dream for up to 3 months. I always double the recipe because it disappears fast—perfect for meal prep. To reheat, cover with foil and bake at 350°F for 20 minutes or until bubbly. The crispy onions on top? Add them fresh after baking so they stay crunchy. Serve with a side of buttery bread to soak up all that creamy goodness.

Step-by-step instructions for Campbell's string bean casserole

This cheesy, creamy classic comes together in one pan—easy, comforting, and packed with flavor!

Trim the ends from the 2 lbs fresh green beans and cut them into 2-inch pieces. In a large skillet, bring 2 cups water to a boil over medium-high heat. Add the green beans and cook for 5-6 minutes until they're bright green and just tender—you want them to still have a slight bite, not mushy. Drain well and set aside.

Here's the thing—if you use frozen green beans, you can skip this step and add them directly to the casserole later. But fresh beans give that classic home-cooked flavor. If you're using the optional 4 oz bacon, cook it now in the same skillet until crispy, then crumble it and set aside to add later.

In a large bowl, whisk together the 2 cans Campbell's Cream of Mushroom Soup, 0.5 cup milk, 2 tbsp melted butter, 2 tbsp all-purpose flour, 0.5 tsp salt, 0.25 tsp black pepper, and 0.5 tsp garlic powder until smooth. This is where the magic happens—the sauce will thicken beautifully and coat every bean perfectly.

I like to give this mixture a quick taste at this stage to adjust seasoning. If it needs more salt or pepper, add it now. The sauce should be thick but pourable—if it's too thick, whisk in 1-2 tablespoons water to loosen it up. This ensures a creamy, not gluey, texture in your final casserole.

Preheat your oven to 375°F. In a 9x13-inch baking dish, combine the cooked green beans, the sauce mixture, and the 2 cups shredded sharp cheddar cheese. Stir everything together until the cheese is evenly distributed and the beans are fully coated. The mixture should look thick and inviting—like a creamy green hug waiting to happen.

Sprinkle the 1 cup crispy fried onions evenly over the top, pressing them gently into the cheese layer. If you cooked bacon earlier, sprinkle those crispy bits on top too. Pop the dish in the oven and bake for 25-30 minutes until the top is golden brown and bubbly, and the edges are slightly crispy.

Remove the casserole from the oven and let it rest for 10 minutes before serving. This resting time is crucial—it allows the cheese to fully melt and the flavors to meld together. You'll notice the top becomes even more golden and the edges crisp up slightly as it cools.

Serve warm straight from the baking dish with crusty bread or over buttered noodles. The creamy mushroom sauce clings to every bean, the sharp cheddar melts in your mouth, and the crispy onions add a delightful crunch. This is comfort food at its finest—simple, satisfying, and full of nostalgia!

Common mistakes when making this recipe

Overcooking Green Beans

I’ve ruined this casserole more times than I’d like to admit by overcooking the green beans—turning them into sad, mushy globs instead of tender-crisp stars. The secret is 5-6 minutes max in boiling water, until they’re bright green and just yielding.

If you’re using frozen beans, skip boiling entirely and add them directly to the casserole mixture. I learned this the hard way after a particularly soggy batch that had me reaching for takeout instead of comfort food. 🥦

Skipping the Resting Time

This one’s a biggie: Never skip the 10-minute rest after baking. I know, I know—you’re starving and that cheese looks perfect, but rushing it means a runny, uneven mess. The rest lets the cheese fully melt and the sauce thicken properly.

Trust me, your taste buds will thank you. Pro tip: Use this time to set the table or grab a cold drink—it’s the perfect pause. ⏳

Using Pre-Shredded Cheese

Pre-shredded cheese is convenient, but it’s the enemy of texture in this casserole. The anti-caking agents make it clump and stay clumpy, even after baking. I’ve tried it—don’t. Instead, grab a block of sharp cheddar and shred it yourself.

If you’re in a pinch, pulse pre-shredded cheese in a food processor for a few seconds to break up the clumps. Your casserole’s creamy dream depends on it. 🧀

Ignoring the Sauce Thickness

The sauce is the soul of this dish, and if it’s too thin, you’ll end up with a watery mess. I’ve seen it happen—someone skips the flour or adds too much milk, and suddenly, you’ve got a sad, soupy casserole instead of the creamy masterpiece you wanted.

The sauce should coat the back of a spoon but still be pourable. If it’s too thick, whisk in 1-2 tablespoons of water to loosen it up. Trust the process! 🥄

Adding Onions Too Early

Crispy fried onions are the crown jewel of this casserole, but adding them too soon kills their crunch. I’ve made this mistake—tossing them in with the sauce or baking them too early, only to end up with soggy, flavorless bits.

Save them for the final 5 minutes of baking, or even better, sprinkle them on top right after removing it from the oven. That way, they stay gloriously crispy and add the perfect crunch. 🧅

Underestimating Leftovers

This casserole tastes even better the next day, but I’ve seen people underestimate how quickly it disappears. Make sure to double the recipe if you’re feeding a crowd or know you’ll be going back for seconds.

Leftovers reheat beautifully—just cover with foil and bake at 350°F for 20 minutes until bubbly. Store in an airtight container for up to 5 days in the fridge. Honestly, I’ve eaten this for breakfast the next morning, and it’s still delicious. 💛

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