Start by bringing a large pot of salted water to a boil. Once boiling, add the rigatoni pasta and cook until al dente, about 10-12 minutes. Drain and set aside.

In a skillet over medium-high heat, heat the olive oil. Add the steak and sear each side for 3-4 minutes. Remove from the skillet and let rest before slicing.

In the same skillet, sauté the diced onion and bell pepper for about 5 minutes. Add minced garlic and cook for another minute.

Pour in heavy cream and deglaze the skillet, scraping any bits. Add blue cheese, oregano, salt, and pepper and stir until melted.

Return the sliced steak to the skillet and fold in the rigatoni until well coated.

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

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