Step 1: Preheat your oven to 375°F (190°C). If using a store-bought or homemade unbaked crust, blind bake it. Line the pie crust with parchment paper and fill it with pie weights or dried beans. Bake for 15 minutes, then remove the weights and parchment and bake for another 5-7 minutes, until lightly golden. Reduce oven temperature to 350°F (175°C).
Step 2: In a large bowl, whisk together the pumpkin puree, granulated sugar, brown sugar, eggs, and egg yolk until well combined and smooth.
Step 3: Stir in the heavy cream (for custard), milk, vanilla extract, cinnamon, ginger, nutmeg, and a pinch of salt. Mix until everything is thoroughly incorporated.
Step 4: Pour the pumpkin mixture into your pre-baked pie crust. Place the pie on a baking sheet to catch any potential spills and make it easier to transfer.
Step 5: Bake at 350°F (175°C) for 50-60 minutes, or until the edges are set and the center jiggles only slightly when gently shaken. A knife inserted near the edge should come out clean. To prevent the crust from over-browning, you can loosely cover the edges with aluminum foil halfway through baking.
Step 6: Let the pumpkin pie cool completely on a wire rack for at least 3-4 hours, or preferably overnight, before adding the ganache. This cooling time is crucial for the custard to set properly.
Step 7: For the ganache, finely chop your dark chocolate and place it in a heatproof bowl. The finer the chop, the faster and more evenly it will melt.
Step 8: In a small saucepan, heat the heavy cream (for ganache) over medium heat until it just begins to simmer around the edges. Do not let it boil vigorously.
Step 9: Pour the hot cream immediately over the chopped chocolate. Let it sit undisturbed for 5 minutes. This allows the heat from the cream to melt the chocolate gently.
Step 10: After 5 minutes, starting from the center, gently whisk the mixture until it becomes a smooth, glossy, homogenous ganache. If it seems a little thick, you can gently warm it over a double boiler or in 10-second bursts in the microwave, stirring well after each.
Step 11: Once the pumpkin pie is completely cooled and set, carefully pour the warm (but not hot!) chocolate ganache over the top, spreading it evenly with an offset spatula or the back of a spoon to create a smooth layer.
Step 12: Refrigerate the pie for at least 2-3 hours, or until the ganache is fully set. This firm ganache makes slicing much easier and cleaner, ensuring a perfect slice every time.