1. Preheat oven to 425 degrees F. Lightly coat a baking dish with cooking spray. In a small bowl, add the raisins and cover with warm water.
2. Spray a large skillet with cooking spray. Add the onions, celery, garlic, and bay leaf. Saute until the onions are translucent (4-5 minutes).
3. Remove the bay leaf and add the apples. Cook until apples just begin to soften (2-3 minutes).
4. Drain the raisins and add to the apple mixture. Stir in the water chestnuts and remove from heat. Let cool.
5. Loosen the skin on the chicken breasts. Place the apple-raisin mixture between the skin and breast. In another skillet, heat the olive oil over medium heat. Add the chicken breasts skin-side down and cook until browned (4-5 minutes). Turn and cook until under side is browned (4-5 minutes).
6. While the chicken is searing, heat the milk, curry powder, and flour over low heat in a saucepan. Stir until the mixture thickens (4-5 minutes).
7. Transfer the chicken breasts to the prepared baking dish, skin-side up. Pour the milk mixture over the chicken breasts. Cover and bake until a meat thermometer registers a minimum temperature of 165 degrees F (15-20 minutes).
8. Serve chicken with the sauce and garnished with lemon.