Preheat the oven to 375°F. Fit the store-bought pie crust into a 9-inch pie pan, trim any excess, and use a fork to lightly dock the bottom. Line the crust with a sheet of foil and add pie weights or dried beans.
Blind-bake the crust for 8 minutes at 375°F to help prevent a soggy bottom. Remove the foil and weights, then return the crust to the oven for 2–3 more minutes until the edge is just set. Lower the oven temperature to 325°F and let the crust cool slightly while you make the filling.
Toast the chopped pecans on a rimmed baking sheet in the warm oven for 5 minutes to deepen their flavor, then transfer them to the pie shell. Reserve the pecan halves for the top decoration.
In a medium bowl whisk the eggs until smooth and slightly frothy. Stir in the packed brown sugar until combined, then whisk in the maple syrup, melted butter, vanilla, salt, and ground cinnamon until the mixture is glossy and uniform.
Pour the filling gently over the toasted pecans in the crust, smoothing the top with a spatula. Arrange the reserved pecan halves on the surface in a single layer or a decorative pattern.
Bake at 325°F for 37–40 minutes, or until the edges are set and the center still has a slight jiggle. If the crust edge browns too quickly, shield it with foil for the last 15 minutes.
Remove the pie from the oven and cool on a wire rack for at least 2 hours at room temperature to let the filling finish setting. For cleaner slices, chill the pie in the refrigerator for an additional hour before serving.
Slice and serve with whipped cream or vanilla ice cream if desired. Store leftovers covered in the refrigerator for up to 4 days.