Preheat the oven to 350 (F). Prepare a 9-inch pie plate by spraying liberally with cooking spray and place the prepared pie plate on a sheet pan.
Combine 9 ounces chocolate graham crackers, 1/4 cup granulated sugar and 1 teaspoon kosher salt in a food processor and pulse in short intervals until the graham crackers have fully crumbled and you have a mixture with the consistency of sand. Transfer to a heatproof bowl, and slowly stir in 1/2 cup (1 stick) melted butter, using a rubber spatula to toss the crumbs together until you have the consistency of wet sand.
Transfer the moist crumbs to your prepared 9-inch pie pan. Use your palms and/or the back of your hand to press the crumbs onto the bottom and up the sides of the plate to create an even, consistent layer. Set aside.
In the bowl of a freestanding electric mixer fitted with a whisk attachment, combine 15 ounces pumpkin puree, 1 cup granulated sugar, 1 tablespoon ground cinnamon, 1/2 teaspoon kosher salt, 2 eggs, and 1 cup plus 2 tablespoons heavy cream. Whisk on low speed until just combined and the mixture becomes a uniform, pale orange color. Transfer 1/2 cup of the pumpkin filling into a small bowl, preferably a liquid measuring cup with a spout. Pour 1/3 cup chocolate chips into the larger bowl of pumpkin filling, before pouring over the prepared pie crust in pie plate. Set aside.
Whisk 2 tablespoons unsweetened cocoa powder into the pumpkin filling until it is a uniform brown — at first the cocoa powder will sit up top the filling and refuse to integrate, so be sure to whisk vigorously.
Pour the chocolate-flavored pumpkin filling on top of orange pumpkin filling in the pie crust, starting in the center and spiraling out towards the edges. At first, the chocolate filling should leave a spiral trail, but the chocolate will expand and cover the top of the orange filling, turning the entire pie a uniform chocolate color.
Bake the pie in the preheated oven for 50 to 60 minutes. Be careful not to overbake! When the pie is finished baking, the edges will have set but it will still be slightly jiggly in the center — the pie will continue to set as it cools. Transfer the finished pie to a wire rack to cool completely, before garnishing with unsweetened cocoa powder before serving.