Prep the zucchini noodles: Spiralize the zucchini and place the noodles on a clean kitchen towel. Sprinkle lightly with salt and let sit for 10 minutes to draw out moisture.
Gently press to remove excess water. This helps prevent soggy zoodles.
Season the chicken: Pat the chicken pieces dry with paper towels. Toss with salt, pepper, paprika, onion powder (if using), and red pepper flakes.
Get the pan hot: Heat a large skillet over medium-high.
Add the olive oil and 1 tablespoon of the butter. When the butter foams and sizzles, the pan is ready.
Sear the chicken in batches: Add half the chicken in a single layer. Cook, undisturbed, for 2–3 minutes to get a good sear.
Stir and cook another 2–3 minutes until just cooked through. Transfer to a plate and repeat with the remaining chicken. Don’t crowd the pan.
Build the garlic butter sauce: Reduce heat to medium.
Add remaining 2 tablespoons butter to the skillet. Stir in the minced garlic and cook 30–45 seconds until fragrant, not brown. Scrape up any browned bits from the pan—that’s flavor.
Return chicken to the pan: Add the cooked chicken and any juices back in.
Toss to coat in the garlic butter. Add lemon zest and a squeeze of lemon juice. Taste and adjust salt and pepper.
Flash-cook the zoodles: Push chicken to one side of the pan.
Add the zucchini noodles to the empty side and toss in the residual sauce for 1–2 minutes, just until slightly tender but still crisp. Overcooking makes them watery.
Finish and serve: Turn off the heat. Toss everything together with parsley.
Sprinkle with Parmesan if you like. Serve immediately with extra lemon on the side.