Heat a large saucepan over medium-high heat until warm.
Add the butter and allow it to melt to coat the bottom of your pan.
Add your steaks to the hot pan and season with salt and pepper.
Allow to cook on one side for 5 minutes, then flip. Season again.
After cooking for 5 more minutes, remove your steaks to a cutting board to rest.
Then, add your onions, green peppers, and mushrooms to the pan.
Cook them until the onions are translucent and the bell peppers are tender.
While the veggies cook, chop your steaks into small pieces.
Add the steak back to the veggie mixture in the saucepan.
Stir everything to combine, and top your mix with the slices of provolone cheese. Reduce the heat to low and allow the cheese to melt.
Don't stir it. Trust me.Once the cheese has melted, scoop your Philly cheese steak into bowls and serve.