Pound and season: If using breasts, lightly pound to even thickness (about 1/2–3/4 inch). Pat dry.
Season both sides with salt, pepper, and paprika. Lightly dredge in flour if using, shaking off excess.
Sear the chicken: Heat olive oil and butter in a large skillet over medium-high. Add chicken and sear until golden and cooked through, about 4–5 minutes per side for breasts, a bit longer for thighs.
Transfer to a plate; tent with foil.
Build the flavor base: Lower heat to medium. Add garlic, red pepper flakes, and chopped sun-dried tomatoes. Cook 30–60 seconds, stirring so the garlic doesn’t burn.
Deglaze: Pour in chicken broth.
Scrape up browned bits from the pan—they’re packed with flavor. Let it simmer 2–3 minutes to reduce slightly.
Make it creamy: Stir in heavy cream and bring to a gentle simmer. Sprinkle in Parmesan and stir until melted and smooth.
The sauce should thicken enough to coat a spoon.
Add greens and brighten: Stir in spinach until wilted. Add lemon juice and taste. Adjust salt, pepper, and heat level as needed.
Finish the dish: Return chicken and any juices to the pan.
Spoon sauce over the top and let it bubble gently for 1–2 minutes to marry the flavors.
Serve: Garnish with fresh basil or parsley. Serve over pasta, rice, or with crusty bread to catch every drop of sauce.