Philly Style Mushroom Cheesesteak

Philly Style Mushroom Cheesesteak

Favorite Cheesesteak

My love of all things East coast runs strong. I was born and raised just about an hour north of Philly – The City of Brotherly Love. While I’ve been living on the West coast for two decades now, there are some things that the East coast just gets right. Take cheesesteaks for example – the beautiful thinly sliced steak, cheese on a Kaiser roll. There are variations of course all over Philly but the idea of the cheesesteak runs strong on the East coast. Not to mention, my father makes a MEAN steak sandwich and used to make them regularly at his pizza shop years ago. He would bake the bread fresh, slice the meat, make the sauce – then placed into the perfect sandwich.

Campbell’s® History

Today I’m thrilled to partner with my friends at Campbell’s® to share one of my favorite ways to enjoy a steak sandwich, mushroom style!!! Funny enough, Campbell’s® began in 1869 back in Camden, NJ – just an hour from where I grew up. It feels good to support a company that ties so closely to my own roots. Not to mention, I know when I’m using Campbell’s® to create dishes, I can count on quality ingredients to make my dish pop.

This post is sponsored by Campbell’s®, all opinions and ideas are my own.

Variety of Cheesesteaks

Steak sandwiches can be made in so many different ways. From traditional steak sauce, adding onions and cheese, topping with mushrooms or pickles and hot peppers. The possibilities are endless and really a perfect vessel to make your own signature sandwich. I’m a HUGE fan of mushrooms and onions, especially on a burger or steak sandwich. Something about the earthy mushrooms that really make a statement. Today I’m using Campbell’s® Cream of Mushroom Soup to create the sauce for my sandwich and topping with sautéed mushrooms and onions for the ultimate steak sandwich.


Steak sandwiches are more than just the meat – but the type of bread you use and the rest of the ingredients including how you top your sandwich is equally important. I’ve gone ahead and listed out various toppings that would go well with this sandwich, of course mine is topped with sautéed mushrooms and onions but some other components that would absolutely be AMAZING! Check out the list of ingredients and option ideas to help guide you to the best sandwich!

Steak – As mentioned above, we’re using flank steak for our sandwiches. That being said, many grocers carry thin sliced carne asada or actual steak sandwich meat that you can ABSOLUTELY use. Those come pre-sliced/shredded and are a huge time saver. You’ll want to still marinade to soak up the flavors but just cook in a hot pan when ready to make.

Campbell’s Cream of Mushroom Soup – Sometimes I really don’t want to go out of my way to make a homemade sauce. Campbell’s® Cream of Mushroom Soup gives me the flexibility to whip up a quick sauce with all the flavor and half the time. We’re going to use the soup as our base, add some garlic, herbs and lots of fresh ground pepper!

Mushrooms + Onions – Mushrooms and onions have my heart on burgers, pizza and obviously steak sandwiches. We’re going to sauté both to create a lovely mixture to top our sandwiches. The best part of this is you can use the leftovers to top pizza, add to omelets or even a grilled sandwich.

Blue Cheese – I know blue cheese isn’t for everyone but with the cream, the mushrooms, the onions – the blue cheese is really elegant and so delicious with this sandwich. You could absolutely use provolone, mozzarella or your favorite cheese.

Jalapenos – Some like it hot, you do you and add whatever hotness level you want. Jalapenos are a great addition to any steak sandwich.

California Style – Some folks call the California style when you add in lettuce and tomato and even mayo. Definitely doable – today I’m just adding a bit of crunchy cabbage for some color and crunch – you do you!

Pickles – Pickles and/or pickled carrots are another great sandwich topper. They add a bit of acidity to an otherwise rich sandwich and can help balance it out.

Bread – Your bread choice is pretty important. You want to use a slightly harder roll – definitely not a hot dog bun which is too soft and squishy. I’m using a Kaiser roll which is definitely soft in the center but is firmer on the outside to ensure nothing soaks through. Toasting the bread is also great to do before loading up to give a firmer base for your ingredients.

Cream of Mushroom Sauce

Sauce is one of the most important components to any cooking, it helps to bring a dish from basic to elegant. Today we’re using Campbell’s® Cream of Mushroom Soup to make a simple but flavorful sauce to top our sandwiches. I love the idea of a cream sauce – it’s reminiscent of steak au poivre and we’re going to add a few ingredients to the soup to make it a little bolder to hold up to our delicious flank steak. This sauce can easily be made ahead as many of the components to help make weeknight dinners a breeze!

Mushrooms and Onions

I adore mushrooms and onions on pretty much anything! I think adding them to these cheesesteaks will really take them over the top and help to highlight our Campbell’s® Cream of Mushroom Soup sauce! One pan to make these mushrooms and onions. A quick sauté of onions, they don’t have to be fully caramelized, I actually like them a tad bit translucent, gives a little more bite. Then a quick cook of mushrooms with some toum or minced garlic and they are done! The best part is they are make ahead and you can use this mixture on pizza, omelets or anything you can think of!

Cooking Flank Steak

The type of steak you use is pretty important when it comes to making the ultimate steak sandwich. Today I’m using flank steak which is a cut of meat that takes well to marinades and cooks very quickly. I’ll be cooking the whole flank piece and slicing our steak into thin strips for our sandwiches. A few things about flank steak to note:

  • Flank steak is very lean, it can be dry and tough if overcooked or sliced too thick.
  • It’s important to cook flank steak to no more than medium and slice very thinly against the grain.
  • Flank steak can be grilled on an outdoor grill or in a grill pan right on your stove. A cast iron grill pan is great for cooking.

With our unpredictable weather, I’m cooking my flank steak in a grill pan on my stovetop.

  • Your steak doesn’t need to marinade long, an hour or so is just fine. Be sure to let your meat come to room temperature before grilling.
  • Once your steak is ready, heat a heavy bottomed pan (cast iron is good here), a grill pan is even better. Heat on high and then place your flank steak – sear for 2-3 minutes.
  • Check to see if it has been seared then flip and repeat on 2nd side. About 3-4 minutes to finish.
  • You can use a meat thermometer in the thickest part of the steak for doneness, you don’t want to go above medium rare:
    120°F for very rare, 125°F for rare, or 130°F for medium rare
  • Remove your pan from the heat and allow steak to rest for 10 minutes before slicing.
  • When slicing, be sure you are making angled cuts AGAINST the grain and cut as thin as possible.


Feel free to experiment with toppings that work for you, or have a steak sandwich bar set up where everyone adds their own toppings. A fun way to get family involved. I like to assemble this way:

Begin by toasting your Kaiser rolls – I give them a little smear of toum or drizzle with olive oil to get a nice golden color.

Next, smear a bit of your Campbell’s® Cream of Mushroom Soup sauce

Then layer your steak, more sauce and finally top with cheese, peppers, shredded cabbage or whatever you are craving!

Quick pop back in the oven to warm it all up and get toasty – and finally, ENJOY!

The beauty of this meal is the ability to make ahead and assemble when you’re ready to eat. The steak can be cooked then stored in the fridge when ready to use, same with the sauce and mushrooms and onions. A simple heat in the microwave or pan to heat then into your sandwich and oven for a broil. This is also great to make using leftover steak!

As always, I love seeing your creations when you share your comments or tag me on social media. You can find Campbell’s® Soups at your local grocer or check their online locator.

Please leave a review or share your dish with me on social media #cosetteskitchen which lets me know what is working for you! You can also tag my friends at Campbell’s®. You can find me on Facebook,  InstagramTwitter and Pinterest. For more delicious recipes to your inbox, sign up for my newsletter!


This post is sponsored by Campbell’s®, all opinions and ideas are my own.

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Philly Style Mushroom Cheesesteak

  • Author: Cosette’s Kitchen
  • Prep Time: 25
  • Cook Time: 20
  • Total Time: 45 minutes
  • Yield: 5 steak sandwiches 1x


A fun and simple meal to get the whole family involved using Campbell’s®. These steak sandwiches are very versatile!



Flank Steak

  • 1.5 pounds flank steak, trimmed*
  • 2 teaspoons kosher salt* (see note about salt below)
  • 2 teaspoons pepper
  • 3 Tablespoons olive oil
  • 2 Tablespoons red wine vinegar, or another similar vinegar
  • 1 teaspoon Italian seasoning
  • 1 heaping teaspoon toum, or 2 teaspoons garlic powder

Mushroom Sauce

  • 2 teaspoons toum, or 3 cloves garlic, minced
  • 1 can (10.5 oz) Campbell’s® Cream of Mushroom Soup
  • 1/2 cup of water
  • 1 teaspoon black pepper
  • 1 teaspoon dry or fresh thyme
  • 1/2 teaspoon kosher salt, adjust as needed*(see note about salt below)

Mushroom + Onion Mixture

  • 8 oz sliced cremini, white or Portobello mushroom
  • 2 large onions, sliced
  • 4 Tablespoons olive oil, divided
  • 1 Tablespoon toum, or 2 cloves garlic minced
  • Kosher salt as needed*

Other Ingredients

  • Kaiser rolls
  • Extra toum or olive oil for toasting bread
  • Blue cheese or your favorite cheese, provolone is also a great option
  • Hot peppers
  • Jalapeños 
  • Shredded cabbage or other green
  • Tomatoes
  • Mayonnaise
  • Anything else you’d like to include on your sandwich 


Flank Steak

  1. Prepare your flank steak by trimming any excess fat.
  2. Mix your marinade ingredients together and place in large sealed bag with flank steak. Allow to marinade for an hour over overnight.
  3. Be sure to remove your steak one hour before cooking to allow to come to room temperature for more even cooking. 
  4. If you have a cast iron grill pan, or any grill pan – you’ll want to use that. Otherwise, a traditional skillet works well. Heat your pan on high for 5 minutes until hot.
  5. Place your flank steak down and allow to sear for 2-3 minutes. You’ll know your steak is ready when you see grill/sear marks and browned.
  6. Flip and repeat on second side for 3-4 minutes.
  7. You can use a thermometer to check for doneness.
    Insert thermometer into the thickest part of the steak: 120F for very rare, 125F for rare and 130F for medium rare. You don’t want to cook beyond that.
  8. Remove pan from heat. Allow steak to rest for 10 minutes before slicing.

Mushroom Sauce

  1. In a small saucepan on medium heat, add your toum – if you are using minced garlic, add 1 teaspoon olive oil and heat garlic until JUST fragrant. Quickly add your soup and water.
  2. Whisk until just combined and add your seasonings.
  3. I always taste before adding salt, especially since the soup is already seasoned. Adjust accordingly.

Mushroom + Onion Mixture

  1. In a 10″ skillet, or something similar heat 2 tablespoons olive oil on medium-high heat. Add your onions and cook for 5 minutes until they begin to brown slightly and become translucent.
  2. Add a teaspoon of kosher salt* and continue to cook for another 5 or more minutes.
  3. I prefer my onions NOT to be fully caramelized for this dish but you certainly can continue cooking to caramelize. 
  4. Remove onions from pan, set aside.
  5. Add 2 tablespoons of olive oil into the same skillet on medium-high heat.
  6. Add your mushrooms and begin to cook for 3-4 minutes until they soften.
  7. As they begin to soften add your toum or minced garlic and cook for another 3-4 minutes. 
  8. Salt at the very END, salting early will release moisture into the mushrooms.
  9. Combine your onions and mushrooms and season as needed. Set aside.


  1. When you’re ready to enjoy your steak sandwiches, take your Kaiser or hard rolls and smear a bit of toum or olive oil on the inside. Place rolls on a sheet pan and into the oven on broil. 
  2. Allow the rolls to brown, this gives a good base for the steak sandwich components and won’t make it soggy.
  3. Once rolls are toasted, begin adding your ingredients –
    a smear of mushroom sauce
    a few slices of steak
    onion mushroom mixture
    more mushroom sauce
    shredded cabbage
    or whatever other toppings you’d like to include…
  4. Place filled sandwiches back into oven on broil for 3-4 minutes until tops are crisp and cheese melts.
  5. Enjoy!



  • Different types of salt have different levels of saltiness – I always season and taste along the way to make sure I have my flavors balanced. Kosher salt tends to be LESS salty than table salt. If using table salt, be sure to HALF the measurement and begin there.
  • An alternative to cooking a whole flank steak is to purchase pre-sliced carne asada or even thinly sliced beef. Season the same way and cook in a hot skillet in batches. 
  • All components can be made ahead and assembled the same you’re ready to eat.
  • Meat can be frozen up to 3 months in sealed packaging. I like to wrap in plastic wrap, then foil and pop into a sealed freezer bag for optimum freshness.

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