Preheat the oven to 400 degrees. Prepare the pie crust by rolling it out and crimping the edge to form a highstanding rim.
For the pecan filling, whisk the eggs in a bowl until foamy. Stir in the corn syrup or maple syrup, brown sugar, vanilla, salt and pecans. Spread the pecan filling over the bottom of the pie crust. Bake for about 20 minutes, until the filling is set and slightly puffed.
Meanwhile, whisk the eggs for the pumpkin filling and stir in the pumpkin puree, milk, brown sugar, cinnamon, ginger, salt, and vanilla until well blended.
When the pecan filling has set, remove it from the oven. Pour the pumpkin filling over the pecan layer and bake for about 40 minutes, until the pumpkin layer is set in the middle.
Decorate by pressing toasted pecan halves around the outside edge of the pie. Cool for at least 20 minutes before cutting. Serve warm or at room temperature.