Bring a large pot of salted water to a boil, add pasta, and cook until al dente. Drain and set aside.
Pat steak strips dry, season with blackened seasoning, and sear in olive oil over medium-high heat until browned and cooked to preference. Remove and keep warm.
In the same skillet, add oil if needed, season shrimp with blackened seasoning, and cook 1 to 2 minutes per side until pink and cooked through. Remove with steak.
Melt butter in the skillet over medium heat, add minced garlic, and cook until fragrant, about one minute.
Pour in heavy cream and simmer gently. Stir in grated Parmesan cheese until melted and sauce is smooth. Season with salt and pepper.
Combine cooked pasta, steak, and shrimp with the Alfredo sauce. Toss gently to coat evenly.
Serve garnished with chopped parsley or additional Parmesan if desired.