Prep the chicken: Pat chicken dry and season both sides with salt, pepper, and a light sprinkle of paprika if using. This helps the chicken sear well and adds flavor from the start.
Sear the chicken: Heat olive oil and butter in a large skillet over medium-high heat. Add chicken and sear 3–4 minutes per side until golden.
Transfer to a plate; it will finish cooking in the sauce.
Sauté aromatics: Lower heat to medium. Add diced onion and a pinch of salt. Cook 3–4 minutes until soft and translucent.
Stir in garlic, Italian seasoning, and red pepper flakes (if using). Cook 30 seconds until fragrant.
Build the base: Add sun-dried tomatoes and stir. Pour in chicken broth, scraping up any browned bits from the pan.
Let it bubble for 1–2 minutes to reduce slightly.
Melt in the cream cheese: Reduce heat to medium-low. Add cream cheese cubes and whisk or stir until mostly smooth and combined.
Finish the sauce: Stir in milk (or cream) and Parmesan. Simmer gently 2–3 minutes, stirring, until the sauce is silky.
Add lemon juice and taste. Season with more salt and pepper if needed.
Return the chicken: Nestle the seared chicken back into the skillet. Spoon sauce over the top.
Cover and simmer on low 5–8 minutes, or until chicken is cooked through (internal temp 165°F/74°C).
Adjust and serve: If the sauce is too thick, thin with a splash of broth or milk. If too thin, simmer uncovered 1–2 minutes. Garnish with chopped basil or parsley.
Serve over pasta, rice, or with crusty bread to soak up the sauce.