Prep the chicken. Pat chicken dry and season on both sides with salt, pepper, and Italian seasoning. Pounding to even thickness (about 3/4 inch) helps it cook quickly and stay juicy.
Brown the chicken. Heat 1 tablespoon of olive oil in a large skillet over medium-high.
Add chicken and sear 4–5 minutes per side until golden and just cooked through. Transfer to a plate and tent with foil.
Build the flavor base. Reduce heat to medium. Add remaining 1 tablespoon oil to the skillet.
Stir in garlic and red pepper flakes and cook 30 seconds until fragrant. Add sun-dried tomatoes and warm through, scraping up browned bits.
Blend the sauce. In a blender, combine cottage cheese, chicken broth, Parmesan, and lemon juice. Blend until completely smooth and silky, about 30–45 seconds.
Taste and add a pinch of salt if needed.
Simmer gently. Pour the blended sauce into the skillet. Bring to a gentle simmer over medium heat, stirring so it doesn’t stick. Cook 2–3 minutes until slightly thickened.
Avoid boiling, which can cause graininess.
Add greens. Stir in spinach and cook 1 minute until wilted. If the sauce gets too thick, splash in a bit more broth to loosen.
Finish the chicken. Return chicken and any juices to the skillet, nestling into the sauce. Spoon sauce over the tops and warm 2 minutes.
Add lemon zest if using. Taste and adjust salt and pepper.
Serve. Top with torn basil and extra Parmesan. Serve with crusty bread, cooked pasta, rice, or mashed potatoes to catch the sauce.