Start by patting your ribeye steaks dry with paper towels. Season both sides generously with salt, black pepper, and garlic powder. Let the steaks sit at room temperature for about 10 minutes to ensure they cook evenly.

Heat your cast iron skillet over high heat with a tablespoon of olive oil. Once the skillet is smoking hot, sear each ribeye for 3-4 minutes per side until you get a deep, golden crust. Remove the steaks from the skillet and allow them to rest for 5-7 minutes. Remember, this resting period keeps the juices intact.

While the steaks rest, lower the heat on your skillet to medium. Add 2 tablespoons of butter and toss in the onions and mushrooms. Cook for about 10 minutes, stirring occasionally, until the onions are golden brown and gentle sweetness develops. Add a pinch of salt for balance.

Once rested, use a sharp knife to slice the ribeye into thin strips, cutting against the grain. Thin slices ensure the steak is tender with every bite.

Cut your hoagie rolls or ciabatta bread in half lengthwise and lightly toast them on a grill or in your skillet. Spread a thin layer of mayonnaise on the bottom half for extra creaminess (optional).

Start layering with slices of provolone cheese on the bottom bread. Add the steak slices, followed by the caramelized onions and mushrooms. Close the sandwich with the top piece of bread, leaving it slightly pressed for easy handling.

For that gooey, melted texture, return the assembled sandwiches to the skillet on low heat. Cover with a lid for 1-2 minutes until the cheese melts beautifully.