Start by bringing a large pot of salted water to a rolling boil. Add rigatoni pasta and cook for about 10-12 minutes, or until al dente. Drain and set aside.

In a large skillet, heat olive oil over medium-high heat. Add steak pieces, searing each side for about 3-4 minutes until browned. Remove and set aside.

Using the same skillet, reduce the heat to medium and add the diced onion and bell pepper. Cook for about 5 minutes until softened. Add garlic and cook for an additional minute.

Pour in heavy cream, scraping the fond from the skillet. Incorporate blue cheese, oregano, salt, and black pepper, stirring gently. Let this simmer for about 3-5 minutes.

Return the seared steak to the skillet, then add the cooked rigatoni to the sauce. Toss gently until the pasta is well-coated with the sauce.

Transfer the mixture into a greased baking dish. Spread it out evenly and top with shredded mozzarella cheese.

Preheat oven to 375°F (190°C). Bake the dish for 15-20 minutes until the cheese is melted and bubbly.

Remove from the oven, let cool for a few minutes, serve hot garnished with chopped parsley.