Combine 8 cups of the milk, sugar and cinnamon in a saucepan and bring to a boil. Simmer, stirring occasionally, 15 minutes.
In a bowl, combine the egg yolks with the remaining milk. Slowly pour into the milk mixture and simmer, stirring frequently, until it reaches the consistency of a thick sauce, about 10 minutes. Stir in the brandy and remove from heat. Pour into a pitcher and chill.