Preheat the oven to 350°F (175°C).

In a large skillet over medium heat, add the ground beef or shredded steak. Cook until browned, breaking it up with a spoon as necessary. Drain any excess grease.

Add the diced onions, bell peppers, and sliced mushrooms to the skillet and sauté until the vegetables are tender, about 5-7 minutes.

Stir in Worcestershire sauce, garlic powder, black pepper, salt, and red pepper flakes, mixing well to combine.

In a large mixing bowl, combine the cooked pasta, sautéed meat mixture, cream of mushroom soup, and 1 ½ cups of shredded provolone cheese. Mix until well coated.

Pour the mixture into a greased 9x13 inch baking dish, spreading it evenly.

Sprinkle the remaining ½ cup of provolone cheese over the top of the casserole.

Place the baking dish in the preheated oven and bake for 25-30 minutes or until the cheese is bubbly and golden brown.

Once out of the oven, let it sit for a few minutes and garnish with fresh chopped parsley before serving.