Preheat the oven: Set to 425°F (220°C). Place a large rimmed sheet pan on the middle rack while it heats. A hot pan helps the skin crisp and veggies caramelize.

Mix the herb oil: In a small bowl, combine olive oil, garlic, rosemary, thyme, oregano, lemon zest, salt, pepper, and red pepper flakes if using.

Prep the chicken: Pat thighs very dry with paper towels. Loosen the skin slightly and rub some herb oil under the skin and all over the thighs. This boosts flavor and crispness.

Season the vegetables: In a large bowl, toss potatoes, bell pepper, red onion, zucchini, and cherry tomatoes with the remaining herb oil. Add a pinch more salt if needed.

Arrange on the hot pan: Carefully remove the sheet pan from the oven. Spread the vegetables in an even layer, then nestle the chicken thighs skin-side up among them, leaving a little space around each piece.

Roast: Cook for 35–45 minutes, until the chicken skin is crisp and the internal temperature reaches 175°F–185°F in the thickest part. Potatoes should be fork-tender and lightly browned.

Finish with lemon: Squeeze the lemon juice over the pan while hot. Toss the vegetables gently to coat, keeping the chicken skin on top so it stays crisp.

Garnish and serve: Sprinkle with fresh parsley and a light shower of Parmesan if you like. Serve straight from the pan with crusty bread or a simple green salad.