1. Place 2 jelly-roll pans in oven. Preheat oven to 450°.
2. Combine onion, carrots, and 1 tablespoon oil in a bowl; toss well. Arrange carrot mixture on 1 preheated pan; sprinkle with 1/4 teaspoon salt. Bake at 450° for 10 minutes.
3. Combine 3/8 teaspoon salt, 1/4 teaspoon black pepper, and next 4 ingredients (through red pepper) in a small bowl. Sprinkle chicken evenly with spice mixture. Heat a small skillet over medium-high heat. Add 1 teaspoon oil to pan; swirl to coat. Add chicken to pan, skin side down; cook 5 minutes or until browned and skin is crisp. Remove chicken from pan. Add chicken to vegetable mixture, skin side up. Bake at 450° for 20 minutes or until chicken is done and vegetables are tender.
4. Combine remaining 1 teaspoon oil, grapes, remaining 1/8 teaspoon salt, remaining 1/4 teaspoon black pepper, and olives in a medium bowl; toss well. Place grape mixture on remaining preheated jelly-roll pan. Bake at 450° for 15 minutes or until grapes are charred and beginning to soften, stirring occasionally. Place 1/2 cup vegetable mixture and 1/2 cup grape mixture on each of 4 plates. Top each serving with 1 chicken thigh. Sprinkle with parsley.