Par-bake the crust: Place oven rack in bottom third of oven and preheat oven to 450°F. Do not prick chilled crust. Line the crust with a double layer of foil. Bake 10 minutes. Remove foil. Reduce oven temperature to 350°F. Return crust to oven to bake 5 minutes more, or until edges are lightly golden and bottom is dry. Remove crust and set aside while you prepare the filling. 

Make the filling: Whisk together eggs, corn syrup, sugar, maple syrup, melted butter, 2 tablespoons bourbon, vanilla extract, and salt in a mixing bowl. Set aside ¾-cup toasted pecan halves and coarsely chop the rest. Scatter the chopped pecans and chocolate on bottom of par-baked pie crust. Add reserved pecan halves for contrasting textures, or save them to garnish the top of the baked pie. Pour egg mixture on top of pecans and chocolate. 

Place pie on a baking sheet in oven. Bake at 350°F, until filling is puffed and set and crust is golden brown, about 1 hour, rotating pie about halfway through. Transfer pie to a baking rack and sprinkle remaining 1 tablespoon bourbon over surface, if desired. Arrange reserved pecan halves, if using, on top of the pie. Let pie cool completely, at least 2 hours. Filling will set further as pie cools. Cover and chill in the refrigerator at least 8 hours before serving. (Once cool, the baked pie can be covered and chilled up to 3 days or wrapped tightly and frozen up to 1 month.) Bring to room temperature, or warm slightly, to serve. Top with bourbon whipped cream (recipe follows below), if desired.

Par-bake the crust: Place oven rack in bottom third of oven and preheat oven to 450°F. Do not prick chilled crust. Line the crust with a double layer of foil. Bake 10 minutes. Remove foil. Reduce oven temperature to 350°F. Return crust to oven to bake 5 minutes more, or until edges are lightly golden and bottom is dry. Remove crust and set aside while you prepare the filling.

Make the pumpkin layer: Stir together the pumpkin puree, brown sugar, pie spice, eggs, cream, and bourbon in a mixing bowl. Pour pumpkin filling into par-baked shell and bake at 350°F for 20 minutes.

Make the pecan layer: Combine eggs, corn syrup, sugar, maple syrup, butter, bourbon, vanilla extract, salt, and chopped pecans in a mixing bowl. Gently spoon on top of pumpkin layer and continue to bake at 350°F for 30 minutes, or until top layer is puffed up, set, and crust is golden brown.

Let pie cool completely, at least 2 hours. Filling will set further as pie cools. Cover and chill in the refrigerator at least 8 hours before serving. (Once cool, the baked pie can be covered and chilled up to 3 days or wrapped tightly and frozen up to 1 month.) Bring to room temperature, or warm slightly, to serve. Top with bourbon whipped cream (recipe follows), if desired.

Bourbon whipped cream: Beat the cream and powdered sugar with an electric mixer at medium speed to soft peaks; add the bourbon. Beat to stiff peaks.

Tip: If crust begins to brown before the pie has set, cover the edges with strips of aluminum foil during the last half of baking.