Season the chicken with salt and pepper. Heat olive oil in a large pot or dutch oven over medium-high heat. Sear the chicken until browned and cooked through, about 4-6 minutes per side. Remove chicken from pot and set aside.
Lower heat to medium, add onion, and cook until soft, about 4 minutes. Add garlic, sun-dried tomatoes, tomato paste, Italian seasoning, and red pepper flakes. Stir and let mixture get fragrant for about 1-2 minutes.
Pour in the broth and bring to a simmer. Add orzo and cook until just tender, about 8 minutes.
Shred (or chop) chicken and return it to the pot. Stir in heavy cream and parmesan until cheese is melted and mixture is smooth.
Add spinach and basil and cook until wilted, 1-2 minutes. Taste and add more salt and pepper if desired.