1. In a large bowl, mix granulated sugar, flour, 1 teaspoon cinnamon, nutmeg, and allspice. Add pears and lemon juice; mix.
2. Mound fruit in bottom crust of pie pastry in pan so that it's higher in the center than at the edges. Cut 2 tablespoons butter into small pieces and dot over pear mixture.
3. On a lightly floured surface, with a lightly floured rolling pin, roll remaining pastry into a 1/8-inch-thick round about 12 inches wide. Center over fruit. Fold edge of top pastry under edge of bottom one flush with pan rim; crimp together to seal. Flute edge decoratively. With a small, sharp knife, cut several slits in top pastry. Set pie in a foil-lined 12-inch pizza pan or 10- by 15-inch baking pan.
4. Bake on the bottom rack of a 375° oven until juices bubble under slits near center of pie, 50 to 55 minutes (40 to 45 minutes in a convection oven).
5. In a 1- to 1 1/2-quart pan over medium heat, stir 3 tablespoons butter until melted. Stir in brown sugar, honey, and 1 teaspoon cinnamon; cook, stirring often, until mixture bubbles all over, 2 to 4 minutes. At once, stir in nuts and spoon mixture evenly over hot pie. Let cool on a rack about 3 hours. Cut into wedges.