1. Preheat oven to 350°.
2. Arrange bread in a single layer on a baking sheet. Bake at 350° for 25 minutes or until golden. Place bread in a large bowl.
3. Heat a large skillet over medium heat. Add oil to pan; swirl to coat. Add celery and next 6 ingredients (through salt) to pan; cook 15 minutes or until vegetables are tender, stirring occasionally. Add celery mixture, chestnuts, and raisins to bread; toss well. Combine chicken broth and egg, stirring with a whisk. Add broth mixture to bread mixture, tossing gently to combine. Spoon bread mixture into a 13 x 9-inch glass or ceramic baking dish coated with cooking spray. Bake at 350° for 50 minutes or until top is lightly browned.