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Thanksgiving Leftover Turkey and Mashed Potato Casserole

Thanksgiving leftover turkey and mashed potato casserole layers hot turkey gravy, peas, and carrots beneath creamy mashed potatoes and sharp cheddar. Baked in a 9x13-inch dish, it turns leftover turkey into a bubbling, cheesy casserole with a golden top.
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Prep Time 15 minutes
Cook Time 43 minutes
resting 10 minutes
Total Time 1 hour 8 minutes
Servings: 8 servings
Course: Dinner
Cuisine: American
Calories: 350
Ingredients Equipment Method Notes

Ingredients
  

For the filling
  • 1 nonstick cooking spray for greasing
  • 2 tbsp unsalted butter
  • 0.5 cup yellow onion finely chopped
  • 0.5 cup celery chopped
  • 1 cup frozen peas and carrots
  • 3 cup cooked turkey chopped or shredded
  • 2 cup turkey gravy
  • 0.25 tsp black pepper
For the topping
  • 0.25 cup milk
  • 4 cup mashed potatoes prepared
  • 1 cup sharp cheddar cheese shredded

Equipment

  • 1 9x13-inch baking dish
  • 1 12-inch skillet

Method
 

Cook the filling
  1. Heat the oven to 375°F.
  2. Coat a 9x13-inch baking dish with nonstick cooking spray.
  3. Melt the butter in a 12-inch skillet over medium heat.
  4. Add the onion and celery and cook for 4–5 minutes, stirring, until softened.
  5. Stir in the peas and carrots, turkey, gravy, and black pepper; cook for 5–7 minutes, stirring often, until the mixture is hot and simmering.
Prepare the topping
  1. Stir the milk into the mashed potatoes until they are easy to spread.
Assemble and bake
  1. Spread the turkey mixture in the prepared baking dish.
  2. Spread the mashed potatoes evenly over the turkey mixture.
  3. Sprinkle with the cheddar.
  4. Cover the dish with foil and bake for 20 minutes.
  5. Remove the foil and bake for 10–15 minutes, until the filling is bubbling and the center reaches 165°F.
  6. Rest the casserole for 10 minutes before serving.

Notes

For even portions, spread the mashed potatoes into an even layer before baking. Refrigerate leftovers for 3–4 days; this casserole can be frozen. For a dairy-free variation, use dairy-free butter, milk, and cheddar.