In a Dutch oven, heat the oil from the sun-dried tomato jar over medium heat for about 1 minute. Add the chopped yellow onion and minced garlic, sautéing for 3-4 minutes until the onions are translucent and fragrant.

Stir in the tomato paste and the julienne-cut sun-dried tomatoes. Cook for 2 minutes until the mixture becomes a rich, velvety consistency.

Pour in the chicken broth and heavy whipping cream, followed by fresh basil, kosher salt, dried Italian seasoning, garlic powder, and crushed red pepper. Bring to a gentle boil, then reduce heat and let simmer for about 12 minutes.

Add the uncooked medium shell pasta, lower the heat, and cook for another 12 minutes, stirring occasionally until the pasta is al dente.

Reduce the heat further, then stir in the fresh baby spinach, shredded rotisserie chicken, room temperature cream cheese, and finely shredded Parmesan. Stir frequently for about 5 minutes.

Ladle into bowls, garnishing with additional Parmesan, fresh basil leaves, and a sprinkle of red pepper flakes. Serve with crusty bread or fresh salad.