Prep the chicken: Pat the chicken dry and slice large breasts horizontally to make cutlets about 1/2 inch thick.
Season both sides with 1 teaspoon salt, 1/2 teaspoon pepper, and 1 teaspoon Italian seasoning.
Heat the skillet: Set a large skillet over medium-high heat. Add 1 tablespoon olive oil. When the oil shimmers, add the chicken in a single layer.
Brown the chicken: Sear 3–4 minutes per side until golden and just cooked through.
Remove to a plate and tent loosely with foil. Don’t overcrowd; work in batches if needed.
Sauté the garlic: Reduce heat to medium. Add 1 tablespoon olive oil and 2 tablespoons butter.
Stir in the minced garlic and a pinch of red pepper flakes. Cook 30–60 seconds until fragrant—don’t let it brown.
Deglaze and simmer: Pour in the chicken broth. Scrape up the browned bits from the skillet.
Simmer 2–3 minutes to reduce slightly.
Make it creamy: Stir in the milk or cream. Bring to a gentle simmer. Sprinkle in the Parmesan gradually, stirring until smooth.
If using Greek yogurt, remove the pan from heat and whisk it in now to prevent curdling.
Brighten the sauce: Add lemon zest and a squeeze of juice. Taste and adjust salt and pepper. The sauce should be savory, garlicky, and a little tangy.
Add greens: Stir in spinach or kale.
Cook 1–2 minutes until wilted and tender.
Return the chicken: Nestle the chicken back into the sauce and spoon sauce over the top. Simmer 1–2 minutes to warm through and let flavors mingle.
Finish and serve: Sprinkle with fresh parsley and extra Parmesan. Serve hot with your favorite sides—cauliflower rice, steamed broccoli, whole-grain pasta, or a crisp salad.