Preheat the oven to 350℉. Stir together the Graham cracker crumbs, powdered sugar, and melted butter until combined. Press firmly into the bottom and up the sides of a pie pan. Bake in the preheated oven for 10-12 minutes or until golden and fragrant. Let cool slightly on a wire rack while you make the custard.

In a medium-sized saucepan, whisk together the granulated sugar, cornstarch, and salt. Scrape the seeds out of a vanilla bean pod. Add the seeds and pod into the pot along with the milk and whisk until incorporated.

Begin heating the milk mixture over medium heat while whisking constantly until the mixture boils and thickens. Remove from the heat. In a separate heat-safe bowl, whisk together the egg and egg yolks for 30 seconds until smooth.

Temper the egg mixture by adding ¼ cup at a time of the hot, thickened milk mixture into the bowl while whisking briskly. Add about 1 cup total into the bowl, whisk until fully combined, and then add the tempered egg mixture back into the pot over medium heat and cook, while whisking, just until the mixture boils and thickens slightly to bring the eggs up to temperature.

Remove from the heat and immediately whisk in the vanilla extract and butter until smooth. Remove the vanilla bean pods from the custard and discard. Pour the custard into the still-warm baked crust. Let cool at room temperature until only slightly warm before covering and refrigerating for at least 3 hours to firm up the custard layer before adding the blueberry layer.

Gently fold together the fresh blueberries and blueberry jam. Cover and refrigerate to assemble later, or put on top of the custard layer once it has chilled. Serve immediately or cover and refrigerate the fully assembled pie until ready to serve. Serve with lightly sweetened whipped cream and more blueberries, if desired. Enjoy!