Step 1: Cook the Pasta
Bring a large pot of salted water to a boil. Cook the high-protein pasta according to package directions until al dente. Drain and set aside. (Pro tip: Reserve about ½ cup of pasta water to thin the sauce later if needed).

Step 2: Prepare and Cook the Steak
While the pasta cooks, slice the partially frozen steak against the grain into very thin strips. Pat it dry and toss it with garlic powder, smoked paprika, salt, and pepper. Heat olive oil in a large, oven-safe skillet or Dutch oven over medium-high heat. Add the steak in a single layer and sear for 1-2 minutes per side, just until browned. It will finish cooking later. Remove the steak from the skillet and set it aside on a plate.

Step 3: Sauté the Vegetables
In the same skillet, add the sliced onion, bell pepper, and mushrooms. Sauté for 6-8 minutes, until the vegetables have softened and developed some color. Add the minced garlic and cook for one more minute until fragrant. Pour in the Worcestershire sauce and soy sauce, scraping up any browned bits from the bottom of the pan. Return the cooked steak (and any accumulated juices) to the skillet, stir to combine, and then transfer the entire meat-and-vegetable mixture to a bowl.

Step 4: Create the High-Protein Cheese Sauce
In a blender, combine the Greek yogurt, cottage cheese, beef broth, cornstarch, Dijon mustard, and onion powder. Blend on high until the mixture is completely smooth and no lumps of cottage cheese remain. This is the secret to a smooth, high-protein sauce base.

Step 5: Assemble the Casserole
Preheat your oven to 375°F (190°C). Pour the smooth cheese sauce mixture into the now-empty skillet. Heat over medium-low heat, whisking constantly, until the sauce begins to thicken slightly, about 3-4 minutes. Do not let it boil. Reduce the heat to low and gradually whisk in 1 ½ cups of the provolone cheese and all of the cheddar cheese until melted and smooth.

Step 6: Combine Everything
Add the drained, cooked pasta and the Philly cheesesteak mixture (steak and vegetables) to the cheese sauce in the skillet. Stir gently until everything is evenly coated. If the sauce is too thick, add a splash of the reserved pasta water to loosen it.

Step 7: Add the Topping and Bake
In a small bowl, mix the panko breadcrumbs, Parmesan cheese, and melted butter. Sprinkle the remaining ½ cup of provolone cheese over the top of the mac and cheese, followed by the panko mixture. Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the topping is golden brown and the casserole is bubbly around the edges.

Step 8: Rest and Serve
Remove the skillet from the oven (remember the handle is hot!) and let it rest for 5-10 minutes before serving. This allows the sauce to thicken up perfectly. Garnish with fresh chopped parsley and serve hot