Begin by cooking the rigatoni pasta. Bring a large pot of salted water to a boil. Add the rigatoni and cook according to package instructions until al dente. Drain and set aside.
In a large skillet over medium-high heat, melt 2 tablespoons of butter. Add the cut sirloin steak pieces, and season with salt and pepper. Sauté for about 5-7 minutes until the steak tips are browned and cooked to your desired doneness. Remove the steak from the skillet and set aside.
In the same skillet, reduce the heat to medium, and melt the remaining 2 tablespoons of butter. Add the minced garlic and cook for about 1 minute until fragrant, being careful not to burn it.
Return the cooked steak tips to the skillet and toss to coat in the garlic butter. Cook for an additional 2-3 minutes, then remove from heat.
Meanwhile, in a separate pot, heat the cream over medium heat. Stir in the cheddar cheese, Parmesan cheese, garlic powder, onion powder, and season with salt and pepper. Mix until the cheese is melted and the sauce is smooth.
Combine the cooked rigatoni with the cheese sauce, stirring until well coated.
Serve the cheesy rigatoni on plates, topped with the garlic butter steak tips. Garnish with chopped parsley.