Preheat oven to 375°. In a large mixing bowl, stir together flour, sugar and salt. Using a pastry blender or two knives, blend in shortening until mixture resembles very coarse crumbs. Sprinkle with water and stir until dough forms a ball. Wrap ball in plastic wrap and refrigerate at least 30 minutes.
When chilled, cut dough in half. On a lightly floured cutting board or counter, roll each dough half out into an 11-inch circle. Let crusts sit until ready to assemble pie.
Make the filling:
Line a 9-inch pie plate with a 14-inch circle of heavy-duty foil. Spread the 2 tablespoons butter over bottom of lined pie plate, using all the butter.
Press pecan halves (outsides facing down) into butter in a decorative circular pattern around bottom of pie plate. Sprinkle nuts with brown sugar.
Spray edges of foil-lined pie plate with cooking spray; set aside.
In a large mixing bowl, using a wooden spoon, stir together sugar, flour, spices and salt; add pears and toss gently to coat; set aside.
Assemble the pie:
Transfer one of the prepared pie crusts to the pie plate, placing it over pecans; press down evenly. Top with pear mixture and dot with butter.
Cover pears with second pie crust, roll edges under and crimp as desired. Cut several slits in the crust to allow steam to escape.
Bake 10 minutes, then reduce heat to 375° and bake an additional 35 to 40 minutes, or until crust is nicely browned.
Let pie cool 5 minutes, then invert onto a serving plate. To garnish, drizzle pie with caramel topping and serve warm, with whipped cream, if desired.