In a food processor—combine graham crackers, brown sugar, cinnamon, and salt. Pulse until crumbs are fine. For easy clean-up, pour crumb mixture into a medium bowl, then add melted butter. Stir well with a fork, making sure to coat the crumbs until the butter is even in distribution.
Spread crumbs across the bottom of the pie plate. With your hands, a tart tamper, or the back and side of a small measuring cup, press the graham cracker mixture into the bottom and all the way up the sides of the pie plate. Refrigerate for 5-10 minutes.
Preheat the oven to 350˚F. Butter your pie pan with a very light coat, then set aside.
Place the crust on the center oven rack while starting the orange chocolate filling, bake for 7 minutes. When the timer sounds, cool on a wire rack until ready to fill.
Orange Chocolate Filling
Keep the 6 ounces of chocolate, a medium bowl with (optional) cinnamon, a large bowl fit with a fine mesh strainer, the vanilla, a small/medium offset spatula, large spatula and both a 1 and ½ cup measuring cup close to the pie shell.
In a medium saucepan, whisk sugar, cornstarch and salt together. Add the orange juice/zest, milk, heavy cream and eggs. Run a whisk or spatula along the corners and bottom of the saucepan, making sure the mixture is well combined.
Place the saucepan over medium-high heat. Whisk nonstop until the mixture boils and thickens, about 7 minutes. Continue stirring for 60-90 seconds. Remove from heat. Strain mixture through a fine mesh strainer and into a large bowl. Stir in the vanilla. Transfer 1½ cups filling to a medium bowl with chopped chocolate and (if using) cinnamon; stir until smooth. Let mixture cool for 10 minutes, stirring often, then pour the chocolate mixture into the graham cracker crust and smooth with the offset spatula or back of a spoon. Clean your offset spatula or spoon and layer the orange filling over the chocolate, then smooth again.
Cover with parchment or plastic to prevent a film and refrigerate 4 hours to overnight.
Orange Mascarpone Whipped Cream
About 15 minutes before you're ready to serve, chill a medium-size deep (preferably metal or glass) bowl and the beaters from your electric mixer in the freezer.
Start at low-medium speed. Beat the cream, mascarpone, sugar, orange juice/zest and dash of cinnamon until the mixture begins to thicken. Increase the speed towards medium/high and continue until stiff peaks form. Avoid over beating. Place the whipped cream in the refrigerator until ready for use.
Pie Assembly
Pipe or spread the whipped cream and sprinkle with chocolate shavings.
Notes
Adapted from The Perfect Pie. Talk about testing; so thankful to America's Test Kitchen.
If making a cream pie for the first time—at about the seven minute mark, the pastry cream will change or thicken. The consistency should be like pudding.
If you don't have mascarpone, leave out and continue with the recipe (same measurements). If wanting more whip, add an additional 1/4 cup heavy whipping cream.
This pie appears to have a film but there isn't really just a golden time to serve, and that's once the refrigerator chill subsides. In light of this window, let this beauty rest at room temperature for 10-15 minutes before enjoying.