Preheat oven to 250 degrees F. Butter four 1/2-cup ramekins and place into a deep roasting pan.
In bowl, whisk together egg yolks and sugar. Set aside. Slit vanilla bean in half lengthwise and remove seeds. In a small saucepan, over medium heat, combine seeds, bean, and cream and bring to a boil. (If using vanilla extract, add to cream after it comes to a boil.) Remove bean. Add a bit of hot cream to egg mixture, whisking constantly. Whisk in remaining cream in a slow, steady stream. Strain misture through a fine-mesh sieve.
Fill each ramekin half-way with bread. Sprinkle with raisins, chocolate chips, and half the cinnamon. Top with remaining brioche. Pour in cream mixture. Press tops lightly and let stand for 5 minutes or until bread has soaked up most of the cream mixture. Sprinkle with remaining cinnamon.
Place roasting pan in the oven and pour in enough water to come up halfway up the sides of the ramekins. Bake for 35 to 45 minutes or until liquid no longer seeps out of rims when tops are pressed. Remove ramekins from water bath and let cool for 10 minutes.
Run knife around inside of ramekins and invert onto individual plates. Serve with ice cream if desired.