Place a saucepan over medium heat and add 3 cups (750 ml) of milk, the cinnamon stick, and the orange peel. Before the milk starts to boil, turn off the heat and cover the pan. Let it steep for about 15 minutes.

Strain the milk and pour it into a clean saucepan over the heat. Add the sugar and stir.
Dissolve the cornstarch in the remaining milk and add it to the saucepan.

Keep the heat very low. Stir the mixture constantly with a whisk until it thickens. Do not stop stirring to prevent it from sticking to the bottom.

After about 15 minutes, check if it has thickened enough. Tilt the pan to one side; if the mixture doesn't move to the other side, it's ready. This usually takes 20 to 25 minutes.

Prepare a small baking dish and lightly grease it with oil.
Pour in the thickened milk mixture and let it cool. Once cooled, cover with plastic wrap and refrigerate for at least 4 hours.

Remove the set mixture from the mold and cut it into small pieces.
Heat plenty of sunflower oil in a small skillet. When hot, coat the pieces of leche frita.

Beat the egg. Coat each piece first in cornstarch, then in the beaten egg.
Fry on both sides until golden, then place on paper towels to drain excess oil.

Mix some sugar with 1 tablespoon of ground cinnamon and coat the fried leche frita pieces on all sides with this mixture.
For a better understanding of the process, you can watch the video.