In a large saucepan over medium heat, combine whole milk, grated panela, and ground Ceylon cinnamon. Stir continuously until dissolved, about 5-7 minutes.

Dissolve cornstarch in about ½ cup of cold milk until smooth.

Slowly pour the cornstarch mixture into the warm milk while stirring continuously for 2-3 minutes.

Reduce heat to low and cook while stirring gently for about 10-15 minutes until thickened.

Remove from heat and stir in unsalted butter until melted.

Pour the warm natilla into a greased dish or mold. Allow to cool at room temperature for 30 minutes.

Cover and refrigerate for at least 2 hours or until fully set.

Garnish with grated coconut and a sprinkle of cinnamon before serving.