Pumpkin Cream Pie - pastry cream

Method

• Make the pumpkin pastry cream: Combine the milk and pumpkin in a medium saucepan. Set on the stove over medium-low heat, stirring occasionally until it's just starting to steam. Meanwhile, in a medium heatproof bowl, combine the brown sugar, cornstarch, egg yolks, salt, and pumpkin pie spice; whisk until smooth. When the pumpkin-milk is hot, add a small splash to the sugar-egg mixture. Whisk. Add another small splash, whisk. Continue this until you've added about 3/4 of the pumpkin-milk. Now pour the tempered sugar-egg mixture back into the saucepan. Cook on medium-low-whisking slowly but constantly (making sure to scrape along the edges, too)-until the mixture thickens like a dense pudding, with your whisk leaving a distinct trail. (This took me about 6 minutes, but it can significantly vary by your stove.) Remove from the heat. Add the butter and vanilla. Whisk until smooth. Press the mixture through a fine-mesh sieve into a heatproof bowl. Cover the top with plastic wrap to avoid a skin forming, then refrigerate until cool.
• Preheat the oven to 350°F. Grease a 9-inch pie pan with butter.
• Make the gingery graham cracker crust: Combine the cracker crumbs, brown sugar, ginger, and salt in a bowl. Pour the melted butter on top. Mix until the crumbs are completely moistened. If you grab a palmful of the mixture and gently squeeze, it should easily hold together (but not seem overly saturated or greasy). If it doesn't hold together, add another tablespoon of melted butter or even water, mix again, and test again.
• When the graham cracker crust mixture is good to go, press it into the greased pie pan, evenly distributing along the bottom and up the sides (a measuring cup really helps here). Bake for about 13 minutes until the crust is browned. Cool completely at room temperature, then freeze for at least 30 minutes before filling with the pastry cream (this makes filling it a lot easier and neater).
• Make the sour cream whipped cream: Combine the sour cream and brown sugar in a medium bowl. Whisk until smooth. Add the cream and whisk until soft-ish peaks form. You want it a little stiffer than you would for, say, dolloping on top of a sundae, because the pie needs to cut cleanly without the whipped cream slouching all over.
• Assemble the pie: Fill the just-frozen graham cracker crust with all the pumpkin pastry cream, spreading evenly to completely fill the crust. Top with the whipped cream, using a spoon or offset spatula to create swoops and swirls. Chill for at least 1 hour or up to 18 hours before serving. Sprinkle with more pumpkin pie spice just before serving.