Prep the chicken
Pat the chicken breasts dry with paper towels.
Season both sides generously with salt, pepper, and the dried Italian seasoning.
(Optional) For more even cooking, you can lightly pound the thicker side of each breast so thickness is uniform.
Sear the chicken
In a large skillet (10–12″), heat the olive oil over medium-high heat until it shimmers.
Add the chicken breasts (don’t crowd them) and cook 4–5 minutes per side, or until golden brown and the internal temperature reads about 160–165 °F.
Transfer the chicken to a plate and tent loosely with foil while you make the sauce.
Start the sauce
Reduce heat to medium. Add butter to the same skillet. Let it melt, scraping the bottom with a wooden spoon to loosen stuck bits.
Add garlic, stir for 30 seconds until fragrant (don’t let it burn).
Add sun-dried tomatoes, stirring to coat them in the butter-garlic mixture.
Add cream & cheese
Pour in the heavy cream, stirring constantly.
Stir in the Parmesan cheese until melted and smooth.
(If you used half-and-half + cornstarch, the sauce should begin to thicken as you stir.)
Let the sauce simmer for 2–3 minutes until it has thickened slightly.
Add greens & fresh touches
Stir in the baby spinach and optional cherry tomatoes, cooking until spinach wilts.
Squeeze in lemon juice and taste the sauce. Add salt or pepper if needed.
Return chicken to the pan
Nestle the cooked chicken breasts back into the sauce. Spoon sauce over the top.
Let everything simmer together for 3–5 more minutes, until chicken is heated through and fully cooked (165 °F internal).
Turn off heat and sprinkle with fresh parsley.
Serve immediately
Spoon extra sauce over each piece of chicken and get ready for compliments.