Preheat oven to 425°F and line a large rimmed baking sheet with parchment paper.
In a large bowl, whisk together 2 tablespoons olive oil, lemon juice, minced garlic, cumin, paprika, turmeric, coriander, cinnamon, cayenne, salt, and black pepper to create the marinade.
Add chicken pieces to the spice mixture and toss until thoroughly coated. Set aside to marinate while preparing vegetables.
In a separate bowl, toss sweet potato cubes with 1 tablespoon olive oil, salt, and pepper. Spread on the prepared baking sheet.
Roast sweet potatoes for 10 minutes, then remove pan from oven.
Add marinated chicken, red onion wedges, and bell pepper strips around the sweet potatoes on the baking sheet.
Return to oven and roast for 12-15 minutes until chicken reaches 165°F internally and vegetables are tender with caramelized edges.
Add zucchini slices in the last 5 minutes of cooking if desired.
Remove from oven and let rest for 5 minutes. Garnish with fresh parsley and serve immediately.