Preheat the oven to 375°F and lightly grease a baking dish large enough to hold the pepper halves snugly. Place the halved bell peppers cut-side up in the dish and set aside.

Heat olive oil in a large skillet over medium-high heat. Add the steak pieces in batches and sear until browned on the outside but not fully cooked through, then remove from the pan and set aside.

In the same skillet, add the diced onion and optional green bell pepper and cook until softened, about 4–5 minutes. Stir in the garlic and cook for another 30 seconds.

Return the steak to the skillet and season with Worcestershire sauce, salt, black pepper, smoked paprika, and onion powder. Stir well, then add the beef broth and simmer for 2–3 minutes until slightly reduced. Stir in cream cheese, if using, and the provolone cheese until melted and combined.

Spoon the steak mixture evenly into each bell pepper half, packing it in generously. Top each pepper with mozzarella cheese.

Cover the dish with foil and bake for 20 minutes, then remove foil and bake an additional 10 minutes until the peppers are tender and the cheese is melted and lightly golden. Let rest for 5 minutes before serving.