Combine paprika, garlic powder, onion powder, oregano, thyme, pepper, cayenne, and salt.
Pat steak dry, toss with Cajun mix. Rest 15 minutes.
Cook rigatoni in salted water until al dente. Drain (reserve a splash of pasta water).
Heat olive oil in a hot skillet. Sear steak tips 2 minutes per side until browned; remove. Add 2 tablespoon butter, let it melt.
In the same skillet, melt 3 tablespoon butter, add minced garlic, cook 30–60 seconds (don’t brown).
Add heavy cream; simmer gently. Stir in Parmesan and mozzarella until smooth. Season with Italian seasoning, salt, and pepper.
Add rigatoni to sauce; loosen with a splash of pasta water if needed.
Return steak tips to the pan and toss 2 minutes to heat through.
Top with parsley (and optional sesame seeds/green onions if you like). Serve hot.