Place the milk, cinnamon and orange zest in a medium sized saucepan, and put on a medium heat. Bring to the boil, then when bubbles begin to appear, take off the heat and leave to infuse for 5 minutes.
Slice the bread into 1 inch /2½ cm thick slices.
Place the bread in a shallow dish and pour over the flavoured milk, making sure the bread is evenly coated in milk. Leave for a couple of minutes, until the bread has absorbed all the milk.
Beat the eggs together, then pour them onto a plate.
Heat ½ tablespoon of olive oil in a large frying pan over a medium heat.
Using a large spoon or spatula as the bread can be quite soft and fragile, place a slice of milk soaked bread in the beaten egg and coat both sides, then place in frying pan. Repeat with another 5-6 pieces bread, depending how large your frying pan is.
Fry on a medium heat for 3-4 minutes until golden, then flip over with the large spatula, and fry for another 3-4 minutes until golden.
Remove the torrijas from the pan and place on a sheet of kitchen paper towel to drain off any excess oil, then repeat with the rest of the slices of bread and the other ½ tablespoon of olive oil.
Mix the white sugar with ground cinnamon in a small bowl then sprinkle over the warm torrijas.
The torrijas can be eaten warm or cold.