Leftover Roast Beef Casserole

Written by
Diana Rattray
Southern-cuisine expert and cookbook author Diana Rattray has created more than 5,000 recipes articles in her 20 years as a food writer.
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Diana Rattray
Updated 04/08/21
Leftover roast beef casserole recipe in a dish with a serving spoon

The Spruce 
Prep: 15 mins
Cook: 35 mins
Total: 50 mins
Servings: 4 servings
Nutritional Guidelines (per serving)
277 Calories
11g Fat
16g Carbs
29g Protein
See Full Nutritional Guidelines Hide Full Nutritional Guidelines
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Nutrition Facts
Servings: 4
Amount per serving
Calories 277
% Daily Value*
Total Fat 11g 14%
Saturated Fat 5g 25%
Cholesterol 74mg 25%
Sodium 1434mg 62%
Total Carbohydrate 16g 6%
Dietary Fiber 3g 11%
Total Sugars 6g
Protein 29g
Vitamin C 8mg 40%
Calcium 136mg 10%
Iron 4mg 20%
Potassium 978mg 21%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

There are lots of recipes for leftover roast beef and many ways to use it. Make a cottage pie, use it in sandwiches, heat it in your favorite stroganoff sauce, or slice the beef into strips and add it to a tossed salad. Or turn your leftovers into a whole new dinner and make this roast beef casserole.

For this recipe, you can either use canned or prepared beef gravy or make your own from scratch using a roux; don't worry if you don't have the pan drippings from the roast.

This casserole is simply a mixture of cooked roast beef, gravy, and vegetables with a melted cheese topping completing the dish. It's a great spur-of-the-moment dish to fix and serve with boiled or mashed potatoes. It's excellent over rice or noodles as well.

1:43

Click Play to See This Leftover Roast Beef Casserole Recipe Come Together

Ingredients

  • Nonstick cooking spray or oil, for greasing the pan

  • 1 cup frozen pearl onions

  • 1 (10-ounce) package frozen peas and carrots, about 1 1/2 cups

  • 2 cups diced leftover cooked roast beef, 1/4-inch to 1/2-inch dice

  • 1 cup beef gravy, homemade, canned, or made from dry mix

  • 1/2 cup shredded sharp cheddar cheese

Steps to Make It

  1. Gather the ingredients.

    Leftover roast beef casserole recipe ingredients
    The Spruce 

  2. Preheat the oven to 350 F. Lightly grease a 1 1/2-quart to 2-quart casserole dish or spray it with nonstick cooking spray.

    A blue casserole dish on a table
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  3. In a medium saucepan, cover the frozen pearl onions and frozen peas and carrots with water. Bring to a boil.

    Carrots, peas and onions in a pot with water
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  4. Reduce the heat and simmer for about 5 minutes or until the vegetables are tender.

    Cooked onions, peas, and carrots in a saucepan
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  5. Drain the vegetables thoroughly and transfer them to a large bowl.

    Drained and cooked peas, carrots, and pearl onions
    The Spruce

  6. Combine the roast beef with the gravy and then add it to the bowl of vegetables. Mix well.

    Mixed vegetables with leftover beef
    The Spruce 

  7. Transfer the beef and vegetable mixture to the prepared casserole, spreading it out evenly, and top with shredded cheddar cheese.

    Leftover roast beef casserole sprinkled with cheddar cheese
    The Spruce

  8. Bake in the preheated oven for 25 to 35 minutes, or until the filling is bubbling and the cheese has melted.

    Baked roast beef casserole with vegetables and cheese
    The Spruce

  9. Serve and enjoy.

    Serving roast beef casserole topped with melted cheese
    The Spruce

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.

How to Store and Freeze

  • Leftover casserole will keep in the fridge for three to four days in an airtight container. Reheat in the microwave or an oven at low temperature until completely hot.
  • For longer storage in the freezer, the casserole should keep for up to three months if frozen in an airtight container or zip-close plastic bag.

Recipe Variations

  • If you don't have leftover roast beef, use thick-sliced deli roast beef or diced raw meat. Stir-fry the raw beef before combining it with the gravy.
  • Swap the leftover roast beef for browned ground beef in the recipe.
  • Diced leftover lamb or roast pork are some other excellent alternatives, along with beef or pork gravy.
  • The vegetables are interchangeable as well. You can use frozen mixed vegetables, peas, green beans, or diced carrots. If you don't have pearl onions, use 1 medium onion, halved and sliced.

How Do You Moisten Leftover Roast Beef?

When reheating leftover roast beef, try adding a little beef broth to help restore some of the meat's moisture. Incorporating the beef into a moist casserole with gravy can also help restore the meat to its former glory.