Initiating the Process: Whisk together egg yolks and cornstarch, then set aside.
Heat Dynamics: In a medium saucepan, combine the coconut milk, half-and-half, granulated sugar, and salt. Bring this to a boil over medium heat, stirring occasionally.
Egg Yolk Incorporation: Extract about 1/2 cup of the hot mixture and gradually whisk it into the egg yolk and cornstarch blend. This tempers the yolks, preventing them from scrambling.
Confluence: Slowly pour the tempered egg mixture back into the saucepan. The liquid will bubble and thicken almost instantaneously. Cook and whisk for another 1 minute and 30 seconds.
Finishing Touches: Remove from heat and blend in the shredded coconut, softened butter, vanilla, and optional coconut extract.