Bring a large pot of salted water to a boil, then add the rigatoni. Cook for 10-12 minutes until al dente, then drain.

Heat a skillet over medium-high heat and add olive oil. Sear the steak pieces for 3-4 minutes until golden, then remove.

In the same skillet, add more olive oil if needed, then sauté diced onion and bell pepper for about 5 minutes. Add minced garlic and cook for an additional minute.

Lower the heat and add heavy cream, scraping the bottom to deglaze. Stir in blue cheese, oregano, salt, and pepper, cooking until melted.

Return the seared steak to the skillet with the cooked rigatoni, mixing until well coated with the sauce.

Preheat oven to 375°F (190°C). Transfer mixture to a greased baking dish, top with mozzarella, and bake for 15-20 minutes until golden brown.

Remove from oven, let cool for a couple of minutes, and garnish with parsley before serving.