Campbell's String Bean Casserole Recipe: Cheesy Bacon Crunch in One-Pan Magic

This Campbell's string bean casserole recipe delivers the ultimate comfort food experience with its creamy, cheesy layers and crispy bacon crunch. 💛 I first made this version during a particularly busy week when I needed a one-pan solution that could feed my whole family without the fuss.

The secret lies in the perfect balance of tender green beans, rich Campbell's cream of mushroom soup, and that satisfying crunch from crispy bacon and breadcrumbs.

The beauty of this recipe is its simplicity—just a few pantry staples come together to create a dish that's hearty enough for a main course but easy enough for a weeknight dinner.

I've tested it multiple times with different variations, and this method consistently delivers that signature cheesy, creamy texture with a golden, crispy topping that everyone reaches for first. The best part? It all comes together in one baking dish, which means less cleanup for you.

By the time it emerges from the oven, you'll have a steaming, bubbling casserole with layers of flavor—tender green beans, savory bacon, and a rich, velvety cheese sauce that ties everything together. The crispy breadcrumb topping adds a satisfying crunch that contrasts perfectly with the creamy filling.

This is the kind of dish that makes your home smell like a classic American comfort food and leaves everyone asking for seconds.

Whether you're serving it as a side dish for a holiday meal or making it the star of your dinner table, this recipe scales beautifully and can be adapted with gluten-free breadcrumbs or extra cheese to suit your preferences.

Let's get started on creating this nostalgic, crowd-pleasing classic that's been a staple in American kitchens for decades.

Ingredients for campbell's string bean casserole

Just 13 pantry staples transform into nostalgic, cheesy, one-dish magic. 💛

The Campbell's soup is the heart of this dish—grab the cream of mushroom from the canned soup aisle, not the boxed kind. Trader Joe's and Walmart usually have it in stock year-round. For the string beans, frozen is perfect (no chopping!), but fresh works too—just trim the ends and cut into 1-inch pieces. Thick-cut bacon makes all the difference here—it stays crispier longer. I always buy a whole pound and cook it myself; the pre-cooked crumbles from the deli section just don't have the same flavor. The cheddar? Block cheese is non-negotiable—pre-shredded gets gummy when melted. Grab a wedge and shred it yourself.

No Campbell's soup? Homemade mushroom sauce works—sauté mushrooms, garlic, and onions in butter, then add flour and milk to thicken. Short on breadcrumbs? Crushed cornflakes or gluten-free breadcrumbs are great swaps for dietary needs. The bacon can be turkey bacon or even crispy fried onions if you're vegetarian (trust me, it still tastes amazing). Need extra richness? Add a splash of heavy cream to the soup mixture. The flour is just for thickening—if you're watching carbs, you can skip it entirely and just let the cheese do its thing.

This casserole reheats beautifully—5 minutes at 375°F is all it takes. Leftovers keep for 4-5 days in the fridge, and it freezes like a dream for up to 3 months. I always make a double batch because it disappears fast. The secret to the perfect topping? Mix the breadcrumbs with 1 tbsp melted butter before sprinkling—it gets extra crispy and golden. Serve straight from the oven with a side of crusty bread for soaking up all that creamy goodness.

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

This one-pan wonder delivers cheesy, crispy perfection with minimal effort—let's make it!

In a large bowl, whisk together the 2 cans Campbell's Cream of Mushroom Soup, 0.5 cup Milk, 0.5 cup All-Purpose Flour, 2 cups Sharp Cheddar Cheese, 1 tsp Salt, 0.5 tsp Ground Black Pepper, 0.5 tsp Garlic Powder, and 0.5 tsp Onion Powder. Stir until completely smooth—no lumps allowed! This is your flavor foundation, so mix vigorously for about 1 minute. The sauce should be thick but pourable, like heavy cream.

I like to use a whisk for this step because it incorporates air and helps prevent clumping. If the mixture looks too thick after mixing, add 1-2 tablespoons of milk to reach your desired consistency. This sauce is the heart of your casserole, so take your time getting it just right.

If using frozen string bean vegetables, thaw them completely in a colander under warm running water for 2-3 minutes. Drain well and pat dry with paper towels. Cut them into bite-sized pieces if they're still large—you want even cooking and easy eating. For fresh beans, simply trim the ends and chop into similar-sized pieces.

Add the 2 cups prepared string beans and 1.5 cups Cooked Bacon to the sauce mixture. Toss everything together gently but thoroughly. The bacon should be evenly distributed, and the beans should be well-coated in that cheesy goodness. This is where all the magic happens—those smoky bacon flavors marry perfectly with the creamy mushroom sauce.

Preheat your oven to 375°F. Lightly grease a 9x13-inch baking dish with 1 tbsp Olive Oil—this prevents sticking and makes cleanup a breeze. Spread the string bean and bacon mixture evenly across the bottom of the dish, pressing down gently with a spatula to create an even layer.

Here's where we get crispy: sprinkle the 0.75 cup Dried Breadcrumbs evenly over the top of the casserole. For extra crunch, I like to press them down lightly with my fingers so they stick to the sauce. This breadcrumb topping is what gives this casserole its signature crispy finish—don't skip it!

Bake uncovered for 30-35 minutes until the top is golden brown and the edges are bubbling. You'll know it's ready when the breadcrumbs look toasted and the cheese has melted into a smooth blanket over the beans. If it's browning too quickly, tent loosely with foil for the last 5-10 minutes to prevent burning.

Real talk: don't open the oven door during baking. Every time you peek, you risk losing heat and steam, which can make your casserole watery instead of creamy. The first 25 minutes are critical—let it do its thing without interference. The final 5 minutes are when that beautiful golden crust forms.

Remove from the oven and let the casserole rest for 10-15 minutes before serving. This resting period allows the juices to redistribute, ensuring every bite is creamy and flavorful. The top will firm up slightly, making it easier to slice and serve.

Slice into 6 generous portions (that's perfect for your 6 servings) and serve immediately. The contrast of crispy breadcrumbs on top, creamy cheese sauce, and tender string beans with smoky bacon is pure comfort food heaven. Pair it with a simple green salad or crusty bread for the ultimate meal!

Common mistakes when making your campbell's string bean casserole

Overmixing the Sauce

I've made this mistake more times than I'd like to admit—whipping the sauce like you're trying to make meringue. The key is to mix just until smooth, about 1 minute with a whisk. Overmixing develops gluten in the flour, which can make the sauce gummy instead of creamy.

If you're worried about lumps, strain the mixture through a fine-mesh sieve afterward. The texture should be thick but still pourable, like heavy cream. 🥄

Skipping the Resting Time

I learned this the hard way during a family dinner when I couldn't wait to serve the casserole. That 10-15 minute rest is crucial—it lets the juices redistribute so every bite is creamy, not watery.

Cutting into it too soon means you'll end up with a soupy mess instead of that perfect cheesy texture. Trust me, the wait is worth it for that restaurant-quality consistency.

Uneven Breadcrumb Topping

The breadcrumb topping is what gives this dish its signature crunch, so don't just sprinkle it randomly. Spread the 0.75 cup breadcrumbs evenly and press them down lightly with your fingers so they stick to the sauce.

I've seen too many casseroles where the topping clumps in one spot and leaves bare patches elsewhere. For extra insurance, mix the breadcrumbs with 1 tbsp melted butter before sprinkling—they'll get even crispier and stick better.

Peeking Too Often

This is a classic oven mistake that ruins casseroles every time. Every time you open that oven door, you're letting out heat and steam, which can make your casserole watery instead of creamy. Let it bake undisturbed for the first 25 minutes, then only peek if absolutely necessary.

The final 5 minutes are when that golden crust forms—don't interrupt that process! The first time I followed this rule, the difference was night and day. 🔥

Using Pre-Shredded Cheese

This is a non-negotiable in my book. Pre-shredded cheese contains anti-caking agents that make it gummy when melted. Always grab a block of sharp cheddar and shred it yourself using the large holes on your box grater.

The texture difference is dramatic—your casserole will be smooth and creamy instead of clumpy. I keep a wedge of cheddar in my fridge specifically for this recipe.

Not Greasing the Dish

Even if you think your baking dish is non-stick, grease it with 1 tbsp olive oil before adding the mixture. The cheese sauce is rich and can stick to anything, especially if you're using an older or well-loved dish.

I've seen casseroles stuck so tightly they required soaking in warm water to remove. A little oil goes a long way in making cleanup effortless. 🧼

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