Cook the spaghetti in salted boiling water until tender, but al dente, which typically takes around 8-10 minutes. Reserve about 1/2 cup of the pasta water before draining.

In a large skillet, heat 2 tablespoons of olive oil and 1 tablespoon of butter over medium-high heat.

Add the diced onion and sauté until softened and lightly golden.

Add the ground beef and cook until browned, breaking it into crumbles as you go.

Stir in the Cajun seasoning, smoked paprika, Italian seasoning, garlic powder, red pepper flakes, black pepper, and salt when the beef is almost done.

Push the beef mixture to the sides and add the remaining butter and minced garlic to the center. Sauté the garlic until fragrant.

Pour in the heavy cream and reduce the heat to medium. Add the softened cream cheese and stir until smooth and combined.

Mix in the grated parmesan, mozzarella, and cheddar until melted and integrated into the sauce.

Add the cooked spaghetti to the skillet and toss gently to coat with the sauce, adding reserved pasta water as needed for desired consistency.

Allow the dish to sit briefly before garnishing with chopped parsley.