Cook the linguine in salted water until al dente. Reserve about ½ cup pasta water, then drain.

Place the ground beef in a large skillet over medium-high heat. Add 1½ teaspoons Cajun seasoning, smoked paprika, garlic powder, and black pepper.

Cook the beef until well browned, breaking it into medium crumbles and allowing a few edges to caramelize. Drain off excess grease while leaving a small amount in the skillet.

Lower the heat to medium and add the butter and garlic. Stir for about 30 seconds, then sprinkle in the flour and cook for 1 minute.

Slowly add the whole milk and heavy cream, stirring as the sauce begins to thicken.

Turn the heat to low and add the Velveeta and cream cheese. Stir until both are completely melted.

Mix in the cheddar, ½ cup mozzarella, Parmesan, and remaining 1 teaspoon Cajun seasoning. Continue stirring over low heat until the sauce is thick and creamy.

Add the linguine and gently turn it through the beef and cheese sauce. Use reserved pasta water a little at a time only if the sauce needs loosening.

Scatter the remaining ½ cup mozzarella over the pasta. Cover the skillet for 1 to 2 minutes, until the cheese melts across the top.

Finish with chopped parsley if using and a light sprinkle of Cajun seasoning before serving.