Bring to a boil 400 ml of milk, sugar and vanilla pods. In a separate bowl, mix egg yolks, flour and the remaining milk, then add a little warm milk from which the vanilla pods have been removed; mix well, then put it all into the pot. Bring to a boil stirring constantly, sieve and leave to cool. Once cooled, add the mascarpone to the mixture, then put into rather low wide bowls. In a saucepan, melt the brown sugar with about 2 tablespoons of water, heat it until it caramelizes and then sprinkle the surface of each little cake with caramel. This dessert should be eaten right away, and it is not advisable, once the sugar has caramelized, to put it back in the fridge.