Heat oven to 350°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. Cook rice in water as directed on package. In 2-quart saucepan, cook onion and celery in butter over medium-high heat 3 minutes, stirring occasionally. Add garlic; cook 1 minute. Stir in flour; cook 1 minute. Add chicken stock and whipping cream; stir until mixture is smooth and bubbly. Stir in salt, pepper and curry powder. In large bowl, mix cooked rice, chicken, cauliflower, peas and carrots. Add white sauce; stir to combine. Spoon into baking dish.