Creating Steak & Blue Cheese Rigatoni Bake is a straightforward process if you follow these steps:

1. Preheat Oven: Preheat your oven to 375°F (190°C) and grease a large baking dish.
2. Cook Pasta: In a large pot, boil salted water and cook the rigatoni until al dente. Drain and set aside.
3. Sear the Steak: In a large skillet, heat olive oil over medium-high heat. Add sliced flank steak and cook until browned. Remove from skillet and set aside.
4. Sauté Onions and Garlic: In the same skillet, add diced onions and minced garlic. Sauté until softened and fragrant, about 3-4 minutes.
5. Make the Sauce: Pour in the heavy cream, and add salt, pepper, and Italian seasoning. Bring to a simmer and let it thicken slightly.
6. Combine Ingredients: In a large mixing bowl, combine the cooked rigatoni, sautéed onions and garlic, seared steak, and crumbled blue cheese. Mix gently to ensure even distribution.
7. Assemble the Bake: Transfer the mixture to the prepared baking dish. Top with shredded mozzarella cheese.
8. Bake: Place the dish in the preheated oven and bake for 30-35 minutes or until the cheese is bubbly and golden.
9. Cool: Once baked, remove from the oven and let it cool for 10-15 minutes before serving.
10. Garnish: Sprinkle with fresh parsley before serving for an extra touch.

These simple steps will guide you in creating this incredible dish effortlessly.