In a small sauce pan, over medium heat, bring brown sugar, corn syrup and butter to a boil. Stir constantly Remove from heat and pour into greased 9X13 pan. Top with 6 slices of bread. Combine sugar and (half tsp)cinnamon.
Sprinkle half of the mixture over the bread. Place remaining bread on top and sprinkle the remaining sugar mixture. In a large bowl, beat eggs, milk, vanilla, and (half tsp)cinnamon. Pour over bread and chill overnight.
Remove from fridge 30 minutes before baking. Bake uncovered @350 35-45 minutes.
Bread should be light brown and the eggs should be solid. I check at 35 minutes and let go longer if needed.