Prep the chicken: Pat the pieces dry and season with salt, pepper, and a pinch of Italian seasoning. Dry chicken browns better and keeps the sauce from watering down.
Sear the chicken: Heat olive oil in a large skillet over medium-high. Add chicken in a single layer and cook 4–6 minutes, stirring once or twice, until golden and cooked through.
Remove to a plate and tent with foil.
Sauté the garlic: Reduce heat to medium. Add butter to the skillet. When melted, add garlic and cook 30–60 seconds until fragrant, stirring so it doesn’t brown.
Build the sauce: Pour in chicken broth and scrape up any browned bits.
Stir in heavy cream and bring to a gentle simmer.
Add the cheeses: Stir in Parmesan and cream cheese (if using) until smooth. Season with salt, pepper, a pinch of Italian seasoning, and red pepper flakes if you like a little heat.
Wilt the greens: Add spinach and cook 1–2 minutes until just wilted.
Return the chicken: Add the cooked chicken and any juices back to the skillet. Simmer 1–2 minutes to thicken slightly.
If it gets too thick, splash in a little broth.
Warm the “noodles”: Add zoodles and toss gently for 1–2 minutes, just until warmed and slightly tender. Don’t overcook or they’ll release water and thin the sauce.
Finish and serve: Taste and adjust seasoning. Add a squeeze of lemon for brightness if you like.
Garnish with chopped parsley and extra Parmesan. Serve hot.