Butter an 8" square pan. Sprinkle brown sugar in bottom of buttered pan; top with croissant pieces. Sprinkle with raisins. Do not stir. In bowl with wire whisk or hand beater, beat eggs, milk, and one T. sugar until well blended; pour over croissant pieces. Do not stir. In another bowl, mix remaining 3 T. of sugar and cinnamon. Sprinkle evenly over bread mixture. Place pan in larger pan and add hot water to the outside pan to come up the sides about an inch. Place plans in oven and bake 40 - 45 minutes at 350 degrees or until puffed and knife inserted in center comes out clean.