Easy Leftover Chicken and Potato Casserole

Easy Leftover Chicken and Potato Casserole

This casserole is easy to prepare with leftover chicken and potatoes. It makes a nice everyday meal using the leftovers from a Sunday chicken dinner, a rotisserie chicken, or a roasted whole bird. The potatoes can be leftover roasted potatoes or, if you need to cook them separately, simply steam them until tender.

The Spruce Eats / Cara Cormack

Leftover chicken can become dry and a little blah but combining it with a creamy sauce and baking until bubbly gives it new life. Revive your leftovers by turning them into a totally new dish that the whole family will love.

How Long Can You Keep Leftover Cooked Chicken in the Fridge?

Leftover cooked chicken will last up to four days in an airtight container in the refrigerator. It can also be stored in the freezer for up to a month. Defrost overnight in the fridge before using and use right away upon thawing.

How to Adapt This Recipe

There are a thousand little ways to vary this recipe and amp up the flavor. Add leftover cooked veggies, like steamed broccoli, or throw in a handful of mixed frozen vegetables or frozen peas. If you like your casseroles extra saucy, double the flour and milk in the mushroom sauce. Add herbs like thyme to the sauce or the breadcrumb topping. Or swap the cheddar cheese for whatever melty cheese you have lying around—you can even mix and match if you only have little nubbins of different cheeses. Crushed French-fried onions mixed into the topping would be delicious as well.

What to Serve With Chicken and Potato Casserole

Casseroles are rich and hearty, so they are best paired with something fresh and green. A simple side salad goes with everything, but you can also serve this dish with sautéed greens, broccoli, or asparagus. Roasted acorn squash is another delicious way to get in some veggies.

Tips for Making the Best Chicken and Potato Casserole

  • If you don't have a small baking dish, you can bake this casserole in the same skillet you use to sauté the mushrooms and make the white sauce. Just make sure that your skillet is oven-safe.
  • When adding the milk or half-and-half to the mushroom mixture, add it slowly, stirring the whole time. This prevents lumps from forming in the sauce.
  • Because all the ingredients in this casserole are cooked, you can taste the mixture before baking to make sure it has enough seasoning.

Glass Bakeware Warning

For premade casseroles or leftovers that are in a glass baking dish and have been refrigerated, do not place directly into a hot oven as the glass can shatter. Instead, place any cold glass bakeware into a cold oven to warm up while it preheats. Or allow the bakeware to rest outside of the fridge for 30 minutes to reach room temperature while the oven preheats.

“This is a great recipe to spruce up leftover night. It’s a simple casserole that comes together rather quickly. The premise of the recipe is fuel for many variations. Follow the formula and clean out the fridge with other meats and veggies, top it differently, add herbs and spices. There’s little chance of boring leftovers!” —Colleen Graham

Easy leftover chicken and potato casserole tester image A Note From Our Recipe Tester


  • 3 tablespoons butter

  • 8 ounces mushrooms, sliced

  • 1 cup chopped onions

  • 2 tablespoons all-purpose flour

  • 1 cup milk (or half-and-half)

  • Freshly ground black pepper, to taste

  • Kosher salt, to taste

  • 2 cups diced cooked potatoes

  • 2 cups diced cooked chicken

  • 1 cup soft breadcrumbs, optional

  • 2 tablespoons butter, melted, optional

  • 1 cup shredded cheddar cheese (or Monterey Jack), optional

Steps to Make It

  1. Gather the ingredients.

    Ingredients to make a chicken and potato casserole

    The Spruce Eats / Cara Cormack

  2. Preheat the oven to 350 F/180 C/Gas Mark 4. Lightly grease a 2-quart baking dish.

    A buttered baking dish

    The Spruce Eats / Cara Cormack

  3. Heat the butter in a large, heavy skillet or sauté pan over medium heat. Add the mushrooms and onions and cook until tender and lightly browned, about 8 minutes.

    A skilled of cooked mushrooms

    The Spruce Eats / Cara Cormack

  4. Stir the flour into the pan. Cook, stirring, for 1 to 2 minutes.

    Flour added to the skillet of mushrooms

    The Spruce Eats / Cara Cormack

  5. Gradually add the milk or half-and-half, stirring, and cook until thickened, 3 to 5 minutes. Add pepper and salt.

    Cream added to the mushroom and flour mixture

    The Spruce Eats / Cara Cormack

  6. In the prepared baking dish, combine the cooked potatoes, chicken, and mushroom sauce mixture. 

    A baking dish with potatoes, chicken, and creamy mushrooms

    The Spruce Eats / Cara Cormack

  7. If using the breadcrumb topping, toss the breadcrumbs with the melted butter until well coated.

    A bowl of breadcrumbs tossed with melted butter

    The Spruce Eats / Cara Cormack

  8. Top the casserole with the buttered breadcrumbs or sprinkle with shredded cheese.

    A baking dish of potatoes, chicken, and creamy mushrooms topped with buttered breadcrumbs

    The Spruce Eats / Cara Cormack

  9. Bake for 25 to 30 minutes or until hot and bubbly.

    A leftover chicken and potato casserole

    The Spruce Eats / Cara Cormack

Feeling Adventurous? Try This:

  • Other cooked vegetables may be used along with the potatoes. Add 1/2 cup or more of diced, cooked rutabaga or carrots either in place of or in addition to the mushrooms.
  • Add a big handful of frozen peas, thawed frozen broccoli, or frozen spinach that has been thawed, squeezed dry, and chopped.
  • Bring in extra flavor by adding herbs and spices along with salt and pepper. Basil, garlic, oregano, paprika, and parsley are good choices for this dish.

How to Store and Freeze

If well wrapped, this casserole can be stored in the fridge for up to a day before baking or frozen for a month. Defrost in the refrigerator overnight before baking and add 5 minutes to the cooking time.


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