Leftover Roast Beef Casserole

By
Diana Rattray
Diana Rattray
Diana Rattray
Southern-cuisine expert and cookbook author Diana Rattray has created more than 5,000 recipes and articles in her 20 years as a food writer.
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Updated on 09/1/23
Tested by Joan Velush
Prep: 20 mins
Cook: 20 mins
Total: 40 mins
Servings: 4 servings

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.

Casserole with diced roast beef and vegetables in a white ceramic baking dish, with a serving on a white plate

The Spruce Eats / Diana Chistruga

"This casserole is the perfect way to use leftovers from a roast beef dinner. With a mix of peas and carrots to round out the meal and some homemade or prepared beef gravy and grated cheddar you've got a quick and delicious dinner ready to go. Try serving it over egg noodles or mashed potatoes." —Joan Velush

Simple Leftover Beef Casserole with Vegetables/tester image
A Note From Our Recipe Tester

Ingredients

  • Cooking spray, or oil, for the dish

  • 1 cup frozen pearl onions

  • 1 1/2 cups frozen peas and carrots, about 6 1/2 ounces

  • 2 cups diced leftover cooked roast beef (1/2-inch dice)

  • 1 cup homemade or store-bought beef gravy

  • 1/2 cup shredded sharp cheddar cheese

Steps to Make It

  1. Gather the ingredients.

    Ingredients for leftover roast beef casserole recipe gathered

    The Spruce Eats / Diana Chistruga

  2. Position a rack in the center of the oven and heat to 350 F. Lightly grease a 1 1/2-quart to 2-quart casserole dish or spray it with nonstick cooking spray.

    Greased ceramic square casserole dish

    The Spruce Eats / Diana Chistruga

  3. In a medium saucepan, cover the pearl onions and peas and carrots with water. Bring to a boil. Reduce the heat to low and simmer until the vegetables are mostly tender, about 3 minutes.

    Peas, carrots, and onions covered with water in a saucepan

    The Spruce Eats / Diana Chistruga

  4. Drain the vegetables thoroughly and transfer them to a large bowl. Add the roast beef and gravy to the bowl of vegetables. Mix well.

    Peas, carrots, onions, and roast beef cubes stirred together in a mixing bowl

    The Spruce Eats / Diana Chistruga

  5. Transfer the beef-vegetable mixture to the prepared casserole dish, spreading it out evenly. Top with shredded cheddar cheese.

    Vegetables and diced roast beef topped with shredded cheese in a casserole dish

    The Spruce Eats / Diana Chistruga

  6. Bake until the filling is bubbling and the cheese has melted, about 20 minutes.

    Leftover roast beef casserole with melted cheese topping

    The Spruce Eats / Diana Chistruga

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.

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 and vegetables.
  • 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 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.

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.

Nutrition Facts (per serving)
268 Calories
11g Fat
15g Carbs
29g Protein
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Nutrition Facts
Servings: 4
Amount per serving
Calories 268
% Daily Value*
Total Fat 11g 14%
Saturated Fat 5g 24%
Cholesterol 74mg 25%
Sodium 1428mg 62%
Total Carbohydrate 15g 5%
Dietary Fiber 3g 10%
Total Sugars 5g
Protein 29g
Vitamin C 7mg 36%
Calcium 133mg 10%
Iron 3mg 19%
Potassium 963mg 20%
*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.)