Prep the chicken: Pat the chicken dry. Season both sides with salt, pepper, and Italian seasoning. If the breasts are thick, slice them horizontally to make cutlets for quicker, more even cooking.

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

Sear the chicken: Cook undisturbed for 4–6 minutes per side (cutlets need less time; thighs may need more) until golden and just cooked through or the internal temperature hits 165°F (74°C). Transfer to a plate and tent with foil.

Sauté aromatics: Lower heat to medium. Add a little more oil if needed. Stir in shallot (or onion) and cook 2–3 minutes until softened. Add garlic and cook 30 seconds until fragrant. Avoid burning.

Deglaze: Pour in chicken broth and scrape up the browned bits. Let it simmer for 1–2 minutes to reduce slightly.

Build the sauce: Stir in heavy cream and sun-dried tomatoes (if using). Bring to a gentle simmer. Reduce heat to medium-low and cook 2–3 minutes. For a thicker sauce, whisk 1–2 teaspoons flour or cornstarch into a splash of cream or broth first, then stir into the pan.

Add spinach and cheese: Fold in the spinach in batches until wilted. Stir in the parmesan until melted and smooth. Season with salt, pepper, and red pepper flakes to taste.

Finish with brightness: Add lemon zest and a squeeze of lemon juice to wake up the flavors. Start with 1–2 teaspoons and adjust.

Return the chicken: Nestle the chicken back into the skillet. Spoon sauce over the top and simmer 1–2 minutes to rewarm and meld flavors.

Serve: Garnish with fresh parsley or basil. Pair with rice, pasta, mashed potatoes, or crusty bread. Spoon plenty of sauce over everything.