Cook pasta according to package instructions.: The kitchen will fill with the comforting scent of boiling starch, and you want the pasta to be al dente so it holds up when tossed with the sauce. Salt the water generously, it should taste like the sea, because that is your only chance to season the pasta itself. A common mistake is overcooking, which results in mushy pasta that will soak up too much sauce and lose bite. Drain and reserve a cup of pasta water in case you need to loosen the sauce, this starchy water can rescue a too-thick finish.
Season chicken on both sides, with salt and pepper, lemon zest, and 1/2 tsp EACH of garlic powder, Italian seasoning and onion powder. Add olive oil to a large skillet over medium-high heat. Once hot, add seasoned chicken and cook for 3-5 minutes on each side, flipping once, until cooked through. Remove chicken to a plate and tent with foil to keep warm while it rests.: You will smell the citrus oils from the lemon zest right away, which helps the seasoning adhere and gives an aromatic top note. Season evenly so every slice tastes consistent. When searing, the meat should sizzle vigorously, which creates Maillard browning for rich flavor. Avoid crowding the pan, overcrowding lowers the temperature and prevents browning, producing steam instead. Let the seasoned chicken rest after cooking, tented with foil, so juices redistribute and it stays juicy when sliced.
Cook Veggies: Add another tablespoon of oil to the skillet. Once hot, add the chopped zucchini and yellow squash. Season with salt and pepper, 1/2 tsp garlic powder and 1/2 tsp Italian seasoning. Cook, on medium-high heat for 2 minutes. Add minced garlic and cook for 30 seconds.: As the chicken hits the pan you will hear a steady sizzle and see the edges darken into deep golden patches, that crust locks in juices and flavor. The pan should be hot but not smoking, and you will notice the aroma transform into roasted, savory notes. If the chicken browns too quickly and blackens, lower the heat slightly to avoid a bitter crust. Resting under foil keeps the meat warm and tender while you finish the sauce, preventing dry slices when you cut it.
Finish: Add hot cooked pasta to the pan, along with the butter and lemon juice. Toss everything to combine, until butter has melted. Sprinkle with parmesan cheese and toss to combine. Chop the chicken and return to the pan.: The vegetables should sizzle and start to blister at the edges, giving a slight caramelized sweetness that complements the savory chicken . Adding the minced garlic at the end preserves its fragrance and prevents bitterness from burning. Watch closely since minced garlic browns fast, burning will introduce an acrid note. The goal is tender yet slightly crisp vegetables that add texture and freshness to the dish.
Serve garnished with parsley and additional parmesan cheese, if desired.: At this stage you will smell the bright lemon mingling with melted butter and toasty parmesan cheese . Tossing while the pasta is hot allows the cheese to melt into a silky coating, and the sauce will cling to the pasta. If the mixture seems dry, a splash of reserved pasta water will loosen the sauce and create a glossy texture. A common error is adding cheese to a cold pan which causes clumping rather than a smooth sauce, so ensure everything is hot enough for melting.
Serve garnished with parsley and additional parmesan cheese if desired: When plating you should see bright green flecks of parsley and a sheen on the pasta from the butter and cheese, which invites you to dig in. The final aroma should be citrus forward with savory undertones and a hint of herbaceous freshness. Serve immediately for the best texture, since the pasta will continue to absorb sauce as it sits. Holding it too long before serving can lead to a thicker, less vibrant dish, so keep fingers nimble and plates ready for the best presentation.