Heat the oil from the sun-dried tomatoes in a large Dutch oven over medium heat until it shimmers.
Add the chopped onion and minced garlic, stirring often, and cook until softened, about 3 to 4 minutes.
Stir in the tomato paste and chopped sun-dried tomatoes, and cook while stirring constantly until the tomato paste turns a slightly deeper red, about 2 minutes.
Pour in the broth and add the cream, chopped basil, salt, Italian seasoning, garlic powder, and crushed red pepper.
Bring the mixture to a boil over medium heat, stirring occasionally for about 12 minutes.
Add the pasta, reduce the heat to medium-low, and continue cooking, stirring occasionally, until the pasta is al dente, around 12 minutes.
Lower the heat to low and stir in the spinach, cooked shredded chicken, cream cheese, and Parmesan.
Cook while stirring often until the cream cheese and Parmesan are fully melted and the chicken is heated through, about 5 minutes.
Garnish with extra Parmesan, basil, and crushed red pepper, and serve hot.