Cook the pasta: Bring a large pot of salted water to a boil. Cook the protein pasta until just al dente.
Reserve 1/2 cup of pasta water, then drain and set aside.
Season the chicken: Pat the chicken dry. Season with 1 teaspoon salt, 1/2 teaspoon pepper, and half the Italian seasoning.
Sear the chicken: Heat olive oil in a large skillet over medium-high. Add chicken in a single layer and cook 3–4 minutes per side, until golden and cooked through.
Transfer to a plate and tent loosely with foil.
Build the aromatics: Reduce heat to medium. Add butter to the same skillet. Stir in garlic, remaining Italian seasoning, and red pepper flakes.
Cook 30–45 seconds until fragrant, scraping up browned bits.
Add tomatoes and broth: Stir in sun-dried tomatoes and chicken broth. Simmer 2–3 minutes to concentrate flavor and soften the tomatoes.
Make it creamy: Pour in the cream. Simmer gently for 2–3 minutes, stirring, until slightly thickened.
Avoid a hard boil so the sauce stays smooth.
Melt the cheese: Lower heat to medium-low. Stir in parmesan until melted and the sauce turns glossy. Taste and adjust salt and pepper.
Wilt the greens: Add spinach and stir until just wilted.
If the sauce seems too thick, add a splash of reserved pasta water or more broth.
Combine everything: Return chicken and any juices to the pan. Add the cooked pasta. Toss until coated and heated through.
A small squeeze of lemon can brighten the creaminess.
Serve: Top with fresh basil and extra parmesan if you like. Serve hot.