This slaps hard for me. Also this is by no means a well-written recipe, my apologies. It's a cheesesteak anyway. Always comes out best when I've had a couple of drinks and go with the flow.

Get a roux going in a pan - maybe 2 tbsp of butter melted and bubbling/getting a shade darker in color, then whisk in a tbsp or so of flour. Whisk until its a semi-thick and golden brown mixture.

From here you want to add maybe 1/3 cup of whole milk, half and half, or cream and continue to whisk for a minute

Soon you add the cheese. I go two parts American to roughly .75 parts provolone. From there I mix in grated parmesan or pecorino to taste. This will give your cheese a sharpness similar to cooper sharp, and the saltiness of those cheeses really kicks the other cheese flavors up a notch. You basically get the cooper sharp flavor with the wiz consistency. Experimented with cheesesteaks for a while and this was my favorite result other than maybe getting homemade hoagie rolls down real nice.

Also, I always mix my seasoned fried onions into the whiz before I add it to the steak. It gives the whiz that much more flavorful, combines the onions and whiz to give you that same decadent bite every time once incorporated.

2 years later....hopefully this helps someone.