Heat the sun-dried tomato oil in a large pot over medium heat. Add the onion and garlic and sauté for about 5 minutes, until softened and fragrant.
Stir in the tomato paste, Italian seasoning, salt, black pepper, red pepper flakes and sun dried tomatoes. Cook for 1-2 minutes until the paste darkens and caramelizes and all ingredients are coated.
Nestle the whole chicken breasts into the pot and pour in the broth. Bring to a boil, then reduce heat and simmer for 12-15 minutes, or until the chicken reaches at least 165°F.
Remove chicken, carefully shred with two forks, and return it to the pot.
Stir in the gnocchi and cook 3-4 minutes, or until they float and become tender.
Add the half-and-half, Parmesan, and squeezed-dry spinach. Heat through without bringing to a boil.
Taste and adjust seasoning as needed. Serve topped with more Parmesan or fresh basil, if desired.
