Philly Cheesesteak Casserole

Ingredients:
1 lb beef sirloin, ribeye, or flank steak (cut into thin strips or small cubes)
1 medium onion, thinly sliced
1 bell pepper, thinly sliced (green or red, or both)
1 cup mushrooms, sliced (optional, but adds great flavor)
3 cloves garlic, minced
1/2 cup heavy cream
1/2 cup beef broth (preferably low-sodium)
2 tbsp olive oil (or butter)
2 cups provolone cheese, shredded (or mozzarella, or a mix)
Salt and pepper, to taste
1 tsp Worcestershire sauce (optional)
1 tsp Dijon mustard (optional, for extra flavor)
Fresh parsley, chopped (for garnish)
Instructions:
Preheat the Oven: Preheat your oven to 375°F (190°C). Lightly grease a 9×9-inch (or similar-sized) casserole dish with cooking spray or butter.
Cook the Beef: In a large skillet, heat 1 tablespoon of olive oil or butter over medium-high heat. Add the sliced beef and cook for 4-5 minutes, stirring occasionally, until the beef is browned. Season with salt and pepper. Once cooked, remove the beef from the skillet and set it aside.
Sauté the Vegetables: In the same skillet, add the remaining olive oil or butter. Add the sliced onion, bell pepper, and mushrooms (if using). Sauté for 5-7 minutes, until the vegetables are softened and starting to caramelize. Add the minced garlic and cook for another 1-2 minutes, until fragrant.
Make the Sauce: Lower the heat to medium-low. Add the heavy cream and beef broth to the skillet with the vegetables. Stir well and bring it to a gentle simmer for 3-4 minutes to allow the sauce to thicken slightly. If using, add Worcestershire sauce and Dijon mustard. Taste and adjust seasoning with salt and pepper.
Combine Beef and Veggies: Return the cooked beef to the skillet with the vegetables and sauce. Stir everything together until well mixed.
Assemble the Casserole: Transfer the beef and vegetable mixture into the prepared casserole dish, spreading it out evenly. Top with the shredded provolone cheese (or cheese of your choice).
Bake: Place the casserole in the preheated oven and bake for 15-20 minutes, or until the cheese is melted and bubbly. If you want the cheese to brown slightly, you can broil it for the last 2-3 minutes.
Garnish and Serve: Garnish with freshly chopped parsley and serve hot. This dish is great on its own or paired with a side of sautéed spinach or a fresh salad.
Optional Variations:
Add more cheese: If you love extra cheese, you can add some cream cheese or cheddar to the casserole for a richer texture.
Swap the beef: You can use chicken breast or turkey if you prefer a leaner option. For a different flavor, try adding some cooked Italian sausage.
Low-carb veggies: If you want to reduce the carb count even further, you can skip the mushrooms and peppers or replace them with other low-carb vegetables like zucchini or spinach.