Prep the chicken: Pat the chicken dry.
Slice large breasts horizontally to make cutlets, or pound to an even 1/2–3/4 inch thickness for quick, even cooking. Season both sides with salt, pepper, Italian seasoning, and smoked paprika.
Sear the chicken: Heat a large skillet over medium-high. Add olive oil.
When hot, add chicken in a single layer. Cook 3–4 minutes per side until golden with some browning. Transfer to a plate; it will finish cooking in the sauce.
Build the garlic base: Reduce heat to medium.
If the pan looks dry, add a splash of oil. Add minced garlic and cook 30–60 seconds until fragrant. Don’t let it burn.
Deglaze: Pour in the chicken broth.
Use a wooden spoon to scrape up browned bits. Let it simmer 1–2 minutes to reduce slightly.
Make the creamy mixture: In a small bowl, whisk Greek yogurt, 1/2 cup Parmesan, lemon zest, and a squeeze of lemon juice. If you want a thicker sauce, whisk the cornstarch into this mixture.
Combine and simmer: Lower the heat to medium-low.
Stir the yogurt-Parmesan mixture into the skillet. Whisk until smooth. Add a pinch of red pepper flakes if using.
Taste and adjust salt, pepper, or lemon.
Finish the chicken: Return the chicken and any juices to the skillet. Spoon sauce over the top. Simmer gently 4–6 minutes until the chicken reaches an internal temperature of 165°F (74°C).
Garnish and serve: Remove from heat.
Sprinkle with fresh parsley or basil and extra Parmesan. Serve hot with your choice of sides.