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Mac and Cheese Green Bean Casserole

Mac and cheese green bean casserole combines tender elbow macaroni and fresh green beans with a creamy cheddar mushroom sauce. Baked until bubbling and topped with golden French-fried onions, it brings two familiar sides together in one casserole.
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Prep Time 20 minutes
Cook Time 40 minutes
Resting 10 minutes
Total Time 1 hour 10 minutes
Servings: 8 servings
Course: Dinner
Cuisine: American
Calories: 760
Ingredients Equipment Method Notes

Ingredients
  

For the pasta and green beans
  • 1 nonstick cooking spray
  • 4 qt water
  • 1 tbsp kosher salt
  • 1 lb elbow macaroni
  • 1 lb green beans fresh, trimmed and cut into 1-inch pieces
For the cheese sauce
  • 4 tbsp unsalted butter
  • 0.25 cup all-purpose flour
  • 3 cup whole milk
  • 1 can (10.5 oz) condensed cream of mushroom soup
  • 0.5 tsp dry mustard
  • 0.25 tsp black pepper
  • 4 cup sharp cheddar cheese shredded
For the topping
  • 1.5 cup French-fried onions

Equipment

  • 1 9x13-inch baking dish
  • 1 4-quart saucepan

Method
 

Prepare the pasta and green beans
  1. Heat the oven to 375°F.
  2. Coat a 9x13-inch baking dish with nonstick cooking spray.
  3. Bring the water and kosher salt to a boil in a large pot.
  4. Add the macaroni and cook for 2 minutes less than the package’s shortest al dente time.
  5. Add the green beans for the final 4 minutes, then drain.
Make the cheese sauce
  1. Melt the butter in a 4-quart saucepan over medium heat.
  2. Whisk in the flour and cook for 1 minute.
  3. Gradually whisk in the milk and cream of mushroom soup.
  4. Whisk in the dry mustard and black pepper, bring to a simmer, and cook, whisking, for 4 to 6 minutes until thickened.
  5. Remove from the heat and stir in the cheddar until smooth.
Assemble and bake
  1. Stir the cheese sauce into the drained macaroni and green beans.
  2. Transfer the mixture to the prepared baking dish.
  3. Bake uncovered for 15 minutes.
  4. Scatter the French-fried onions evenly over the top.
  5. Bake for 5 to 8 minutes more until the casserole bubbles at the edges and the onions are golden.
  6. Rest the casserole for 10 minutes before serving.

Notes

For the smoothest sauce, shred the cheddar yourself and stir it in off the heat. Refrigerate leftovers for 3 to 4 days; freeze the casserole without the topping for up to 2 months, then add the onions before baking.