Preheat oven to 350°F. Lightly coat a 2-quart rectangular baking dish with cooking spray. Set aside. In a large skillet melt the 1 tablespoon butter over medium heat. Add onion, carrot, sweet pepper, and chile pepper; cook and stir for 6 minutes. Stir in zucchini and garlic. Cook and stir for 3 minutes more.
Stir in broth, rice, the water, tomato paste, and 1 tablespoon of the Tandoori Spice Mixture. Bring to boiling; boil for 1 minute. Carefully pour rice and vegetable mixture into prepared baking dish. Cover tightly with foil. Bake for 45 minutes.
Meanwhile, sprinkle the remaining Tandoori Spice Mixture evenly over all sides of the chicken. Using your fingers, rub spices into the meat. In a large skillet melt the 1½ teaspoons butter over medium-high heat. Cook chicken in hot butter about 4 minutes or just until browned, turning once halfway through cooking. Transfer chicken to plate; chill in refrigerator until needed.
Remove rice mixture from oven and uncover it. Arrange chicken pieces on rice mixture. Replace foil. Bake for 20 to 25 minutes more or until chicken is done (165°F) and rice is tender. To serve, sprinkle with cilantro.
Tips: Because chile peppers contain volatile oils that can burn your skin and eyes, avoid direct contact with them as much as possible. When working with chile peppers, wear plastic or rubber gloves. If your bare hands do touch the peppers, wash your hands and nails well with soap and warm water.