In a mixing bowl, whisk together the olive oil, lemon juice, Greek seasoning, Spike seasoning, dried thyme, salt, and pepper until combined.
Add the chicken thighs to the bowl, ensuring they are well-coated in the marinade. Cover and let them marinate in the refrigerator for at least 30 minutes, or up to 4 hours.
Preheat your oven to 425°F (220°C).
While the chicken marinates, slice the bell peppers and red onion. Rinse the cherry tomatoes and set everything aside.
Once the chicken has marinated, arrange the chicken thighs on one side of the sheet pan. On the other side, spread the sliced vegetables and cherry tomatoes. Drizzle any remaining marinade over the veggies.
Place the sheet pan in the preheated oven and roast for about 30-35 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (75°C).
Once out of the oven, allow the dish to rest for a few minutes. Serve the chicken alongside the roasted vegetables.
