Remove skin from chicken. Cut breasts in half crosswise, if using.To large resealable plastic bag, add yogurt, garlic, ginger, cumin, 1 tsp. chili powder, and 1 tsp. salt. Seal bag to remove air, and squish ingredients together until combined. Add chicken to bag, seal, and shake to coat. Refrigerate at least 30 minutes, or up to 24 hours.Preheat oven to 425°F and place rack in center. Line large-rimmed baking sheet with aluminum foil and coat generously with nonstick cooking spray.Drain and rinse chickpeas, and pat dry with paper towels, removing any loose skins. Place chickpeas in large mixing bowl.Add cauliflower and sweet potato to bowl with chickpeas. Drizzle with olive oil, and sprinkle with remaining chili powder, turmeric, and remaining salt. Toss to evenly coat, and spread into single layer on prepared baking sheet.Remove chicken from bag, and shake off any excess marinade. Arrange piece on top of vegetables, and bake 15 minutes. Remove pan from oven and carefully stir veggies around to promote even cooking. Return pan to oven, and bake 15–20 minutes more, until chicken reaches internal temperature of 165°F and juices run clear when sliced.Squeeze lemon over chicken and veggies, sprinkle with cilantro, and serve.