Preheat your oven to 425°F (220°C). This high temperature will help achieve that beautiful roast on the chicken and vegetables.
In a mixing bowl, combine 3 tablespoons of olive oil, minced garlic, fresh thyme, lemon juice, 1 teaspoon of salt, 1/4 teaspoon of pepper, and onion powder. Whisk everything together until well blended.
Place the chicken thighs in the bowl with the marinade, ensuring they are well coated. Allow them to marinate for at least 15 minutes for maximum flavor. If you have more time, marinate them for up to 2 hours in the refrigerator.
While the chicken is marinating, slice your yellow squash, bell peppers, and mushrooms, and chop the red onion. In a large bowl, toss the vegetables with the remaining 2 tablespoons of olive oil, 1/2 teaspoon of salt, and 1/2 teaspoon of pepper.
Spread the marinated chicken thighs out on one side of a large baking sheet. On the other side, place the seasoned vegetables in a single layer.
Roast everything in the preheated oven for about 30-35 minutes, or until the chicken reaches an internal temperature of 165°F (75°C) and the vegetables are tender and slightly caramelized.
Once cooked, remove the baking sheet from the oven. Let the chicken rest for a few minutes before serving. This will help keep it juicy. Serve the chicken alongside the vibrant roasted vegetables for a meal that’s as beautiful as it is delicious!