Pre-heat oven to 375
In a small sauté pan over a medium heat, melt butter and add onions, celery, and apples. Simmer and stir until soft (approximately 5 to 7 minutes). Stir frequently.
Add cinnamon and sauté for an additional 3 minutes. Take off heat.
In a large bowl, add Challah bread cubes, egg, water, cider, and raisins. Mix thoroughly by hand.
Add in sautéed mixture, and stir until evenly distributed.
Spray down dish with non-stick spray and bake for approximately 25 minutes, or until lightly brown on top.