Begin by slicing your beef sirloin into thin strips for the best texture in your Slow Cooker Cheesesteaks. Next, chop your onions and bell peppers, opting for vibrant colors to enhance flavor and presentation. If using, slice mushrooms as well.

In a generously sized slow cooker, layer the sliced beef sirloin evenly at the bottom, followed by the onions, bell peppers, and optional mushrooms.

Sprinkle your seasonings—steak seasoning, garlic powder, and parsley—over the top, and add dollops of butter or ghee for moisture.

Set your slow cooker to low and cover it with the lid, allowing the ingredients to cook for 6-8 hours or on high for 3-4 hours.

Once your Slow Cooker Cheesesteaks are tender, layer provolone cheese on top of the mixture and let it cook for an additional 5-10 minutes until melted.

Carefully scoop the cheesesteak mixture onto lettuce wraps or hoagie rolls for serving.

For a speedy version, combine all your prepared ingredients in your Instant Pot, ensuring to include beef broth, and cook on high pressure for 9 minutes.