Prep the chicken and zucchini: Pat the chicken dry and season with salt, pepper, and half the Italian seasoning. Slice the zucchini into half-moons about 1/2-inch thick so they hold their shape.

Heat the skillet: Set a large skillet over medium-high heat. Add 1 tablespoon olive oil. When it shimmers, add the chicken in a single layer.

Sear the chicken: Cook without moving for 3–4 minutes to get color. Flip and cook another 2–3 minutes until just cooked through. Transfer to a plate and tent loosely with foil.

Cook the zucchini: Add the remaining oil if needed. Toss in the zucchini with a pinch of salt and pepper. Sauté 3–4 minutes, stirring occasionally, until lightly browned but still crisp-tender.

Add the aromatics: Reduce heat to medium. Push the zucchini to the sides and melt the butter in the center. Add garlic and the remaining Italian seasoning. Stir for 30 seconds until fragrant—don’t let it brown.

Make the sauce: Pour in the chicken broth and scrape up any browned bits. Simmer 1–2 minutes to reduce slightly. Add a small squeeze of lemon juice and a pinch of red pepper flakes if using.

Bring it together: Return the chicken and any juices to the skillet. Sprinkle in the Parmesan and toss gently until the sauce lightly coats everything. If it’s too thick, add a splash more broth; if too thin, simmer another minute.

Finish and serve: Add lemon zest, taste, and adjust salt and pepper. Sprinkle with chopped parsley and extra Parmesan. Serve hot as-is or over rice, orzo, or mashed potatoes.