Melt butter & brown sugar & cinnamon in a small saucepan. Spread half of the Brown sugar mixture in the bottom of a 9x13" pan. I used a non- stick pan. Place 6 slices of bread over Brown sugar mixture.
Spread the remainder of the Brown sugar mixture over the bread. Place remaining 6 slices of bread on top. Beat eggs and milk together. Pour over the top. Cover and refrigerate Overnight. Bake at 350º. For 40 minutes. I sprinkled some cinnamon sugar on top of mine.