Generously pierce the crust with a fork before baking.
Bake according to recipe or according to package directions, until golden brown. Remove from the oven and allow the crust to cool.
In a liquid measuring cup or small bowl, combine ½ cup whole milk and cornstarch. Mix until cornstarch is dissolved. Set aside.
In a medium-sized saucepan over medium heat, whisk together the remaining 1 cup of whole milk, coconut milk, and sugar. Bring to a simmer, whisking often.
Stir the cornstarch mixture once more before slowly adding to the coconut milk mixture, whisking constantly. Continue whisking until the mixture becomes thick, like a thick pudding. (This coconut milk pudding is the haupia.) It is very important that the mixture is thick before moving to the next step.
Place about half of the haupia mixture into a separate bowl and set aside. Add chocolate chips to the remaining mixture in the saucepan and stir until the chocolate chips are completely melted and well combined.
Add the chocolate haupia mixture immediately to the cooled pie crust and smooth with a spatula until even.
Carefully add the remaining haupia mixture over the top and carefully smooth over until even.
Cover and refrigerate for 6 hours.