Prep the chicken. Pat the chicken dry and season generously with salt, pepper, paprika, and Italian seasoning. This builds flavor from the start.
Brown the chicken. Heat 1 tablespoon olive oil in a large skillet over medium-high.
Add chicken in a single layer. Cook 4–6 minutes, turning once, until browned and just cooked through. Transfer to a plate and cover loosely.
Sauté aromatics. Lower heat to medium.
Add remaining 1 tablespoon oil to the skillet. Stir in onion with a pinch of salt. Cook 2–3 minutes until softened.
Add garlic and red pepper flakes; cook 30 seconds until fragrant.
Steam the broccoli. Add the chicken broth to the skillet and bring to a simmer. Stir in broccoli. Cover and cook 3–4 minutes, until bright green and crisp-tender.
If using frozen broccoli, cook 1–2 minutes longer.
Make the sauce. Reduce heat to medium-low. Add cream cheese cubes and stir until melted and smooth. If the sauce looks too thick, add a splash more broth.
Taste and season with salt and pepper.
Combine and enrich. Return chicken and any juices to the pan. Stir gently to coat in the sauce. Add Parmesan and lemon juice if using.
Simmer 1–2 minutes until everything is hot and the sauce clings to the chicken and broccoli.
Finish and serve. Sprinkle with chopped parsley. Serve as-is or spoon over rice, mashed potatoes, or pasta. For extra richness, drizzle a teaspoon of olive oil over each portion.