Start by bringing the milk, sugar, lemon zest, and cinnamon stick to a boil in a saucepan. Once it starts boiling, remove from heat and let it cool.

When the milk is cool, place slices of day-old bread in a bowl and use a large spoon to pour the milk mixture over the bread. The slices should be well soaked.

Carefully turn the slices so they absorb the liquid on both sides. While you heat oil in a skillet, remove the soaked bread slices from the milk and place them on a rack.

Prepare a plate lined with paper towels (to drain excess oil), a bowl with sugar and ground cinnamon (for coating the torrijas), and a deep plate with the beaten eggs.

Once everything is ready, dip the bread slices in the beaten egg and fry them right away. When golden on one side, flip to brown the other side.

After frying, place the bread on the paper towel-lined plate to absorb excess oil. Then, while still warm, carefully coat each slice in the sugar and cinnamon mixture.

Repeat this process with all the bread slices.