Cook the pasta according to the package directions until al dente. Drain and set aside.
Heat the olive oil in a large skillet over medium-high heat.
Season the chicken with the salt, black pepper, and Italian seasoning. Add it to the skillet and cook for 6 to 8 minutes until golden and fully cooked. Transfer to a plate.
In the same skillet, add the garlic and sun-dried tomatoes. Cook for 1 minute until fragrant.
Melt the butter, then stir in the flour and cook for 1 minute while stirring constantly.
Gradually whisk in the chicken broth, then stir in the heavy cream. Simmer for 3 to 4 minutes until the sauce begins to thicken.
Stir in the Parmesan cheese until melted and smooth.
Add the spinach and cook for 1 to 2 minutes until wilted.
Return the cooked chicken to the skillet, then add the cooked pasta. Toss until everything is evenly coated in the sauce.
Garnish with fresh basil or parsley and crushed red pepper flakes, if desired, before serving.