Heat oven to 400°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. In 12-inch skillet, melt 2 tablespoons butter over medium heat. Cook onion in butter 5 minutes, stirring frequently, until tender. Stir in garlic and rice; cook 1 minute. Spoon mixture into baking dish. In same skillet, melt remaining 2 tablespoons butter over medium heat. Cook sweet potatoes, parsnips and carrots in butter 6 minutes, stirring occasionally. Spoon vegetables over rice mixture. Add broth, thyme and rosemary to skillet. Stir in chicken, cheese, whipping cream, salt and pepper. Add to baking dish; stir until well combined.