Prep the chicken. Pat the chicken dry and slice breasts horizontally into cutlets, or use thighs as-is. Season lightly with salt and pepper on both sides. This helps the chicken brown well and stay juicy.

Heat the skillet. Add olive oil and butter to a large skillet over medium-high heat. Once hot and shimmering, add the chicken in a single layer. Don’t crowd the pan.

Brown the chicken. Sear for 4–5 minutes per side until golden and cooked through (165°F internal temp for breasts; thighs may need a minute more). Transfer chicken to a plate and tent loosely with foil.

Sauté aromatics. Reduce heat to medium. If the pan looks dry, add a small knob of butter. Add chopped onion and cook 2–3 minutes until softened. Stir in minced garlic for 30 seconds until fragrant.

Deglaze and season. Pour in the chicken broth and use a wooden spoon to scrape up the browned bits. Stir in the ranch seasoning until dissolved. Let it bubble for 1–2 minutes.

Make it creamy. Reduce heat to medium-low. Whisk in heavy cream and the cream cheese (if using) until smooth. Simmer gently for 3–4 minutes to thicken slightly, stirring often. Avoid a hard boil to prevent curdling.

Add Parmesan and balance. Stir in Parmesan until melted. Taste and adjust with a pinch of salt, pepper, and a squeeze of lemon juice for brightness.

Optional veggies. If adding mushrooms, sauté them in the sauce for 3–4 minutes until tender. For spinach, fold it in and cook 1 minute until wilted.

Return the chicken. Nestle the chicken back into the skillet and spoon sauce over the top. Simmer 2–3 minutes so the flavors come together. The sauce should coat a spoon.

Serve. Garnish with chopped parsley or chives. Serve hot over rice, pasta, or mashed potatoes, with extra sauce on top.