If your graham cracker crust requires prebaking (or if using a packaged crust that recommends it), prebake according to package or recipe instructions, then let the crust cool completely.
Place the dark chocolate chips and the heavy cream in a microwave-safe bowl. Microwave in 20–30 second bursts, stirring well between bursts, until the chocolate is fully melted and the mixture is smooth. Let the ganache cool until it is warm to the touch but not hot.
In a stand mixer or with a hand mixer, beat the room-temperature cream cheese and the powdered sugar together on medium speed until smooth and lump-free, scraping down the bowl as needed.
With the mixer on low speed, slowly pour in the cooled chocolate ganache and beat just until the filling is evenly combined and smooth. Do not overmix.
Pour the filling into the cooled graham cracker crust and smooth the top with a spatula.
Refrigerate the pie for at least 4 hours, or until the filling is fully set. Serve chilled.