Main Courses
This Campbell's string bean casserole recipe brings back the comforting flavors of classic home cooking—creamy, cheesy, and topped with that perfect golden mushroom crunch. 💛 I first made this version after realizing my Nonna's original recipe needed a modern twist that still kept the heart of the dish intact.
The secret lies in balancing the creamy Campbell's soup base with crispy mushrooms and a buttery, cheesy topping that browns to perfection.
What makes this recipe special is its simplicity—just a few key ingredients that come together in layers for maximum flavor. You'll start with string beans, mushrooms, and cream of mushroom soup, then build up with a rich cheese sauce and a crispy topping that adds texture.
The best part? It bakes in 35 minutes at 350°F, making it perfect for a weeknight dinner that feels like a homemade hug. The combination of creamy, crunchy, and savory elements makes every bite satisfying.
By the time it comes out of the oven, you'll have a dish that's creamy, cheesy, and topped with golden, crispy mushrooms that add a satisfying crunch.
The aroma alone will have everyone gathering around the table, and the flavor is rich enough to stand on its own or pair with a simple green salad. This is the kind of comfort food that reminds you why home cooking is worth the effort.
Whether you're serving it for a family dinner or bringing it to a potluck, this casserole delivers restaurant-quality results with minimal fuss. The instructions are straightforward, and the ingredients are easy to find, making it a foolproof recipe that even beginners can master. Let's get started!
Ingredients for campbell's string bean casserole
Just 13 ingredients for a casserole that tastes like Nonna's hug—creamy, cheesy, and topped with golden mushroom crunch!
| Ingredient | Amount | Notes |
|---|---|---|
| Campbell's Cream of Mushroom Soup 🍄 | 2 cans | Condensed, 10.5 oz each |
| Fresh String Beans 🌱 | 2 lbs | Trimmed, cut into 1-inch pieces |
| White Mushrooms 🍄 | 1 ½ lbs | Sliced into 1/4-inch pieces |
| Shredded Cheddar Cheese 🧀 | 2 cups | Medium sharp, freshly grated |
| Butter 🧈 | ½ cup | Unsalted, melted |
| All-Purpose Flour 🌾 | ¼ cup | For creamy sauce base |
| Milk 🥛 | 1 cup | Whole milk preferred |
| Breadcrumbs 🍞 | ½ cup | Panko for extra crunch |
| Garlic Powder 🧄 | 1 tsp | Freshly ground preferred |
| Onion Powder 🧅 | 1 tsp | For savory depth |
| Salt 🧂 | ½ tsp | Kosher or sea salt |
| Black Pepper 🌶️ | ¼ tsp | Freshly cracked |
| Dried Parsley 🌿 | 1 tbsp | For garnish, optional |
The Campbell's Cream of Mushroom Soup is the secret weapon here—it's got that perfect umami depth that makes this dish sing. Grab the condensed version (10.5 oz cans) for the right texture, not the ready-to-serve kind. For the mushrooms, white or cremini work best—they brown beautifully and hold their shape. I always buy mine from Trader Joe's because their pre-sliced mushrooms save time, but fresh is better if you've got it. The string beans? Fresh is ideal, but frozen works in a pinch—just don't thaw them first. Look for bright green beans with crisp ends, and trim the ends before cutting them into even pieces (that's where the magic happens!).
No cream of mushroom soup? Substitute with cream of celery soup plus 1 tbsp mushroom powder—it's close enough! Running out of butter? Olive oil works, but it won't give that same rich, golden crust. The cheddar matters—medium sharp is perfect, but sharp works too. If you're in a bind, Monterey Jack melts just as nicely. For the breadcrumbs, Panko is a game-changer—it stays crispy even after baking. No Panko? Regular breadcrumbs toasted in the oven for 5 minutes first will help. The garlic and onion powders? Diamond Crystal kosher salt is my go-to for seasoning—it's got a cleaner taste than table salt.
This casserole reheats like a dream—honestly, it's even better the next day. Store leftovers in an airtight container for up to 5 days in the fridge. For freezing, let it cool completely, then portion into individual servings with foil over the top. It keeps for 3 months frozen, and you can pop it straight into the oven from frozen (just add 10 minutes to the bake time). The best part? It doubles as a great make-ahead dish for potlucks—just cover it with foil while it bakes, then uncover for the last 5 minutes to get that golden top.
Why You'll Love This Recipe
- Five-Ingredient Magic: I swear, this is the kind of dish where you look at the pantry and think, "Wait, I already have everything?" Campbell’s soup does the heavy lifting—just toss in beans, mushrooms, and cheese, and let the oven work its magic. No chopping, no fuss, just pure satisfaction.
- Creamy Mushroom Hug: That velvety Campbell’s soup meets buttery mushrooms and melty cheddar? It’s like a warm, savory blanket for your taste buds. The string beans add just enough snap to keep it interesting—no soggy, sad casserole here.
- Leftovers That Don’t Suck: Honestly, I make this on Sundays because it reheats like a dream. The cheese stays gooey, the beans stay tender, and it’s still delicious the next day—no sad, dry reheats. Perfect for lunches or when you just don’t feel like cooking.
- Budget-Friendly Crowd-Pleaser: Mushrooms and cheese might sound fancy, but they stretch far in this dish. I feed my whole family (plus my picky teen) for under $10, and no one complains. It’s the kind of recipe that makes you feel like you’re serving something special without breaking the bank.
Step-by-step instructions for Campbell's string bean casserole
This cheesy mushroom casserole delivers the ultimate comfort food experience—crispy golden top, creamy mushroom sauce, and tender string beans in one perfect dish!
🍳 Step 1: Make the Creamy Mushroom Sauce
Melt the 0.5 cup butter in a large saucepan over medium heat. Once melted, whisk in the 0.25 cup all-purpose flour and cook for 1-2 minutes until bubbly but not browned. This creates a roux that will thicken our sauce beautifully.
Slowly pour in the 1 cup milk while whisking constantly to prevent lumps from forming. Stir in the 2 cans Campbell's Cream of Mushroom Soup, 1 tsp garlic powder, 1 tsp onion powder, 0.5 tsp salt, and 0.25 tsp black pepper. Bring the mixture to a gentle simmer and cook for 5-7 minutes until it thickens slightly. You're aiming for a smooth, velvety sauce that coats the back of a spoon—this is the flavor foundation of our casserole!
👨🍳 Step 2: Prepare the Vegetables
While the sauce simmers, trim the 2 lbs fresh string beans and cut them into 1-inch pieces. Slice the 1.5 lbs white mushrooms into ¼-inch pieces. I like to use a sharp chef's knife for this—it gives you clean cuts and prevents the mushrooms from turning to mush.
Give the string beans a quick rinse under cold water to remove any dirt, then drain well. The mushrooms don't need rinsing, but I do pat them dry with a paper towel to remove any moisture. This helps them brown nicely when we cook them later. Keep both vegetables separate for now—we'll combine them in the next step.
🥘 Step 3: Assemble the Casserole
Preheat your oven to 350°F. In a large mixing bowl, combine the cooked string beans and sliced mushrooms. Pour the creamy mushroom sauce over the vegetables and stir gently to coat everything evenly. You want every bean and mushroom piece to be fully coated with that rich, flavorful sauce.
Transfer the mixture to a 9x13-inch baking dish, spreading it out evenly. Sprinkle 1 cup of the shredded cheddar cheese evenly over the top. The cheese will melt into the casserole, creating that irresistible cheesy pull you love in comfort food!
🔥 Step 4: Create the Crispy Topping
In a small bowl, mix together the 0.5 cup breadcrumbs, remaining 1 cup shredded cheddar cheese, and 1 tbsp dried parsley. This is where the magic happens—this topping will give us that perfect golden, crispy crust that everyone goes crazy for!
Sprinkle the breadcrumb mixture evenly over the entire surface of the casserole. Use a spoon or your fingers to gently press it down so it sticks to the cheese underneath. This ensures maximum surface area for that beautiful golden browning. Pop it in the preheated oven and bake for 30-35 minutes until the top is golden brown and bubbly, and the edges are crispy.
⏰ Step 5: Rest and Serve
Remove the casserole from the oven and let it rest for 5-10 minutes before serving. This resting time allows the cheese to set slightly and makes it easier to cut clean slices. The casserole will be hot and bubbly—perfect for serving family-style!
Here's the thing—this casserole tastes even better the next day when all those flavors have had time to meld together. The crispy topping might soften slightly, but trust me, it's worth the wait. Serve with a side of crusty bread to soak up all that creamy goodness, and you've got a weeknight dinner that feels like a hug in a dish!
Pro Tips For Making Campbell'S String Bean Casserole
- Trim and Blanch Beans: DESCRIPTION:
- Sauté Mushrooms First: DESCRIPTION:
- Skip the Pre-Bake: DESCRIPTION:
- Use Sharp Cheese: DESCRIPTION:
Flavor customization for this dish
Spicy Kick Option
For a little heat, stir 1 tbsp hot sauce (like Crystal or Tabasco) into the creamy mushroom sauce before assembling. I also add ½ tsp cayenne pepper to the breadcrumb topping for extra zing. If you love heat, try ½ tsp smoked paprika in the sauce for depth. 🌶️
Herb-Infused Twist
Swap the dried parsley for 2 tbsp fresh dill or thyme in the breadcrumb topping. I also like adding 1 tsp dried basil to the sauce for a fresh, aromatic touch. Fresh herbs add brightness that balances the richness perfectly.
Protein Boost
Add ½ lb cooked bacon (crumbled) or 1 cup cooked ground beef to the vegetable layer for extra heartiness. For a vegetarian option, stir in 1 cup cooked lentils or ½ cup crumbled feta cheese before baking. The protein adds staying power to this already satisfying dish.
Extra Cheesy Variations
Swap the cheddar for Monterey Jack (milder) or Gruyère (nutty). For a decadent version, mix ½ cup cream cheese into the sauce before baking. I also love adding ¼ cup shredded mozzarella to the breadcrumb topping for extra stretch and gooeyness.
Vegetarian-Friendly Swaps
Replace the Campbell's cream of mushroom soup with 2 cups vegetable broth thickened with 2 tbsp cornstarch. For extra richness, stir in ½ cup nutritional yeast to the sauce. The dish stays hearty and satisfying without any animal products.
Crispy Topping Upgrades
For extra crunch, mix ¼ cup crushed cornflakes into the breadcrumb topping. I also like adding 2 tbsp grated Parmesan for umami depth. Toast the breadcrumbs in a dry pan for 2 minutes before mixing to enhance their flavor even more.
Nutrition facts
Frequently asked questions
Can I use frozen string beans instead of fresh?
Yes! Frozen string beans work perfectly—just don't thaw them first. Drain and pat them dry before mixing with the mushrooms and sauce. The texture will be slightly softer than fresh, but the flavor stays rich and satisfying. For best results, use high-quality frozen beans without added sauces.
How do I make this casserole ahead of time?
You can assemble the casserole up to 24 hours in advance and refrigerate it uncovered. When ready to bake, add 10-15 extra minutes to the baking time (cover with foil for the first 20 minutes to prevent over-browning). For freezing, bake completely, then cool and store in an airtight container for up to 3 months—reheat covered at 350°F for 20 minutes.
Why did my topping turn soggy instead of crispy?
Soggy topping usually means one of two things: either the breadcrumbs weren't toasted first or the casserole baked too long covered. For crispiness, press the topping firmly before baking and uncover for the last 5-10 minutes to let it brown. Try toasting the breadcrumbs in a dry pan for 2 minutes before mixing with cheese to boost crunch.
What's the best way to reheat leftovers?
Reheat in the oven at 350°F for 15-20 minutes covered with foil, then uncover for 2-3 minutes to restore crispiness. Microwaving works too (covered for 2 minutes on medium-high), but the texture won't be as crisp. For best results, reheat just before serving to maintain that golden crunch.
Can I make this gluten-free?
Replace the breadcrumbs with ½ cup crushed gluten-free crackers or ½ cup gluten-free panko-style breadcrumbs. For the roux, use a gluten-free flour blend. The texture will be slightly different but still delicious. Just ensure all other ingredients (like Campbell's soup) are certified gluten-free if needed.