Melt butter; add brown sugar and apples and simmer 1 to 2 minutes.
Pour into 9" by 13" pan and let cool.
Beat together eggs, milk, and vanilla.
Slice bread in half and layer over apples to cover whole dish.
Pour egg mixture over all making sure all bread is wet.
Sprinkle with cinnamon.
Bake at 350° until golden brown and puffy for 40 to 50 minutes.
Cut into squares and serve with powdered sugar or favorite syrup.