Bring a large pot of salted water to a vigorous boil. Add spaghetti and cook according to package instructions until al dente, typically around 8-10 minutes. Once cooked, drain the spaghetti, then drizzle with a touch of olive oil to prevent it from sticking together, and set aside to keep warm.

While the spaghetti is cooking, pat the thinly sliced chicken breasts dry with paper towels. Season both sides generously with Cajun seasoning, smoked paprika, salt, and pepper for extra flavor. Next, press grated Parmesan cheese onto each piece of chicken, ensuring a nice coating for a crispy texture when cooked.

In a large skillet over medium heat, add a tablespoon of olive oil and half of the salted butter. Once the butter has melted and the pan is hot, place the chicken in the skillet. Sear for 4-6 minutes on each side until the chicken is golden brown and fully cooked, reaching an internal temperature of 165°F. In the last minute of cooking, add minced garlic and sauté until fragrant.

Remove the cooked chicken from the skillet and set aside, covering it to keep warm. In the same skillet, add the remaining butter and melt it over medium heat. Sauté another minced garlic clove until fragrant, then pour in the heavy cream and low-sodium chicken broth. Stir to combine, bringing the mixture to a gentle simmer.

Whisk in the softened cream cheese until fully incorporated and smooth. Gradually add shredded mozzarella, sharp cheddar, and a sprinkle of grated Parmesan cheese, stirring until melted. Season the creamy sauce with Italian seasoning, adjusting salt and spices to taste. Allow it to simmer gently for a few minutes until slightly thickened.

Add the cooked spaghetti directly into the skillet with the creamy Cajun sauce. Toss everything together until the spaghetti is thoroughly coated and warmed through, about 2-3 minutes on low heat.

To plate, divide the creamy spaghetti onto serving plates. Top generously with the sliced parmesan-crusted chicken for added appeal. Garnish each plate with freshly chopped parsley for a burst of color and flavor, and serve hot.