Heat the milk in a frying pan with the cinnamon and sugar. In a small bowl mix the cornstarch with a little of the hot milk. Stir until smooth.
Add a small amount of the hot milk, mix well and pour into a pan.
Stir the egg yolks (without beating them) and add another small amount of the warm milk. Stir rapidly until smooth.
Add more milk and pour it into the pan. Cook over a low flame.
Stir occasionally until the mixture starts to thicken a little (scrape the bottom of the pan so it does not stick). Add the vanilla and remove from the flame.
Heat the oven to 177°C.
Heat about ⅛ cup of oil in a frying pan and fry the tortillas on both sides until leathery but not crunchy.
Add more oil if necessary. Drain the excess oil and line the bottom of an oven dish (preferably made of glass).
Cut the plantain in pieces. Fry them on both sides until brown. Drain the excess oil and set aside.
Place a layer of bread on top of the tortillas, sprinkle with a third of the drained prunes, pecans, and raisins, and add a third of the plantains. Remove the stick of cinnamon from the boiled custard mixture.
Pour 1½ cups of the custard very slowly over the first layer and let the bread absorb the liquid. (If you pour it too fast, it will just go to the bottom of the oven dish.) Repeat with a second layer and then a third.
Bake for 40 minutes or until most of the liquid has been absorbed.