Combine the coconut milk, evaporated milk, and condensed milk in a pot. Simmer for 5 minutes.
Dissolve the cornstarch in fresh milk in a separate bowl.
Add the corn into the pot.
Whisk in the cornstarch slurry into the pot and heat until the mixture thickens.
Brush sides and bottom of a deep baking dish with coconut oil.
Pour the maja blanca into the oiled dish.
Leave at room temperature for an hour.
Chill in the rerigerator for at least 2 hours.
Slice and optionally serve topped with toasted coconut shavings.