Preheat your oven to 425°F and line a large sheet pan with parchment paper for easy cleanup. This temperature ensures vegetables caramelize while chicken cooks through perfectly without drying out.
Pat chicken pieces dry with paper towels, then place them on your prepared pan. Arrange sheet pan chicken and veggies by grouping similar-sized pieces together so everything cooks evenly in 25 minutes.
Combine garlic powder, paprika, dried thyme, salt, black pepper, Italian seasoning, and red pepper flakes in a small mixing bowl. Sprinkle this seasoning mixture over chicken and vegetables, drizzle with olive oil and lemon juice, then toss thoroughly until everything is coated.
Spread the chicken and vegetable mixture in a single layer, ensuring nothing overlaps. Roasting in one even layer prevents steaming and guarantees crispy exterior textures throughout the meal.
Place in preheated oven and roast for 20-25 minutes, checking halfway through. Chicken is done when internal temperature reaches 165°F and vegetables are fork-tender with slightly crispy edges.
Remove from oven and let rest for 3-5 minutes before serving. This short rest allows juices to redistribute, keeping your pan dinner moist and flavorful.