Season both sides of chicken breasts with 1 ½ teaspoon salt, pepper and Italian seasoning.
In a large nonstick skillet, heat 3 teaspoons olive oil over medium heat, and when hot, add seasoned chicken breasts. Cook for 5 minutes on one side, until browned, then flip and continue to cook until an inserted digital thermometer reads 160°F, about 3-4 more minutes. Remove from the heat and set aside on a cutting board.
Add remaining 1 ½ teaspoons oil along with the onion and bell pepper, season with remaining salt, and continue cooking on medium heat until vegetables are translucent and just start to brown around the edges, about 5 minutes. Add in garlic, garlic powder, onion powder, and Cajun seasoning, and cook until fragrant, about 1 minute more.
Pour in the wine, chicken stock, and Worcestershire sauce. Let come to a vigorous simmer and allow to cook until reduced by one-third, about 5 minutes.
While cooking, thinly slice the cooked chicken breasts.
Once the liquid is reduced, reduce heat to medium low and stir in Velveeta and soup until smooth, about 3 minutes.
Pour in tomatoes, 3 tablespoons Parmesan, parsley, and sliced chicken. Mix well.
Place half your spaghetti in a large serving bowl, then pour half of the sauce on top. Mix together gently with tongs. Repeat with the remaining spaghetti and sauce, then top with remaining Parmesan and parsley and serve immediately.