finished philly cheesesteak sandwiches

Philly Cheesesteak Sandwich – A Roast Beef Leftovers Recipe

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Have leftover roast beef and don’t know what to do with it? Tired of regular roast beef sandwiches but don’t want food to go to waste? This simple yet flavorful and delicious recipe for an open-faced Philly cheesesteak sandwich is quick and easy and is the perfect way to use up our leftover Roast Beef Perfection!

I’m a busy mom who is always looking for easy recipes for after school and after work. Also, being a family of 6 means we need to watch our budget.

Nothing frustrates me more than throwing food in the garbage. Using leftovers is at the top of my list of quick and easy recipes – especially for weeknights!

Our delicious Philly Cheesesteak Sandwich is ready in minutes utilizing leftover steak and leftover beef roast. Cut down on wasting leftovers and whip up a quick easy meal in no time! This recipe tastes amazing!

Not very often do we have leftover roast beef, but when we do I like to whip up a whole new dish with it. This is a quick and easy-to-make meal that is absolutely delicious.

For this post, I’m going to show you how to make it from our leftover roast beef recipe which I hope has become a favorite for your family too!. You can also use leftover steak or cook up some fresh meat if you prefer.

Utilizing leftovers certainly can be challenging sometimes, and I hope this recipe helps you save time AND money!

Philly Cheesesteak Sandwich Recipe from roast Beef Leftovers

Total Time: 30 minutes start to finish.


  • cutting board
  • knives (for slicing meat, veggies, and bread knife)
  • cheese grater
  • large frying pan and lid
  • tongs
  • cookie sheet
  • parchment paper

Philly Cheesesteak Sandwich Ingredients

  • 2-3 cups leftover roast beef
  • 1 large onion
  • a red pepper
  • a yellow pepper
  • 1 cup mushrooms
  • a mix of spices (seasoning salt, Montreal steak spice, pepper)
  • 5 tbsp Hoisin Sauce
  • 3-4 tbsp Worcestershire sauce
  • 5 tbsp Oyster Sauce
  • 1/4 cup original Kraft BBQ sauce
  • a loaf French bread
  • 1 cup old cheese
  • 1 cup mozzarella cheese
  • Alternatively, use 2 cups of marble cheese.
Our delicious Philly Cheesesteak Sandwich is ready in minutes utilizing leftover steak and leftover beef roast. Cut down on wasting leftovers and whip up a quick easy meal in no time! This recipe tastes amazing!

Cooking Instructions

Step 1: Preheat oven to 400ºF

If you decide to use fresh meat for this recipe you will need to cook it up first and season then come back to this step.

Step 2: Make Philly Cheesesteak Mixture

Slice onions peppers and mushrooms into slices.

First things first, chop up all of the peppers, mushrooms and onions into slices and strips. Then toss them into a medium temp frying pan and cover with a lid.

Sauté onions peppers and mushroom slices.

Slice up the leftover roast beef into long thin strips. Once onions and peppers begin to soften up and have cooked a bit then add the roast beef strips to the frying pan and cover again.

If you have leftover cooked steak, that works well too.

Now add in the hoisin sauce, oyster sauce, Worcestershire sauce and BBQ sauce. Make sure to mix well so that everything is nicely covered in flavor. You may add 1/4 cup of water if needed, however, it most likely won’t be necessary because peppers and mushrooms have a lot of moisture.

Add leftover roast beef strips to pan as well as sauces.

Next, season the Philly Cheesesteak mixture with a blend of spices. Because the meat was seasoned in its original cooking process, not much seasoning is required now.

Add a bit more seasoning to your Philly cheesesteak sandwich mixture

Mix well and simmer until meat is reheated. This only takes a minute or two because the meat is in nice thin slices.

Simmer until fully heated. Your Philly cheesesteak topping is ready for the next step.

Step 3: Bake the open-faced Philly Cheesesteak Sandwich!

Slice French bread into 1-inch slices. Lay a sheet of parchment paper on the cookie sheet, then place the slices of bread on top.

Using parchment paper will help make clean up a snap.

Slice French bread into 1 inch slices

Grate the cheese, which I always get my husband to do because I don’t have a GRATE track record (I love puns!) with cheese graters haha.

Use approximately 1 cup of each type of cheese or 2 cups of marble cheese if you prefer.

Grate 1 cup of old cheddar and 1 cup of mozzarella. Alternatively substitute with 2 cups of marble

Put a little bit of cheese on your French bread to add some extra yummy goodness.

Put a bit of cheese on the French bread.

Using tongs, add some of your Philly cheesesteak mixture on top of the cheese covered bread. Tongs make this so easy to get the perfect amount nice and evenly dispersed on the bread.

Add some Philly cheesesteak topping to your sandwich

Add the remainder of cheese on top of the Philly cheesesteak mixture.

If you love cheese, add a sprinkle of parmesan on top for extra cheesiness!

Top your Philly cheesesteak sandwiches with remainder of cheese

Bake in the oven at 400°F for 10 mins or until cheese melts and bread is a bit crisp. Carefully remove from oven and serve.

Finally, enjoy your meal!

Bake at 400ºF until cheese melts

And that’s a wrap… well a sandwich 😉

If you have leftover mashed potatoes and carrots from your roast beef perfection dish they also make a great side for this meal and another way to use up some more leftovers.

Enjoy your Philly cheesesteak sandwich with you favourite side dishes or leftover mashed potatoes and carrots.

Get our roasted garlic mashed potato recipe here!

You can use any of your favorite side dishes too! We love to pair it with fresh home fries when we don’t have other leftovers that need to be used up.

Your whole family will love these, and your guests will ask for the recipe! I would love it if you shared our blog with them. I hope this recipe becomes a family favorite in your home too!

This is a quick and easy way to use up leftovers which can be completed in under half an hour! The taste is amazing and most certainly will have your family asking for more.

Click here for more of our favorite family recipes!

I hope you enjoyed this Philly cheesesteak sandwich recipe and come back for more. Follow us on Pinterest so you never miss a thing! Bon Appétit!

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