Prepare and roll pastry for single-crust pie, Line a 9" pie plate with pastry. Trim; crimp edge as desired.
In a large bowl stir together eggs, pumpkin, and half-and-half. Stir in sugar, flour, lemon peel, vanilla, salt cinnamon, nutmeg, and allspice.
Pour pumpkin mixture into pastry-lined pie plate, To prevent overbrowning, cover edge of pie with foil. Bake in 375 F oven for 25 minutes.
Meanwhile, in a medium bowl stir together the brown sugar, pecans and butter until combined. Remove foil. Sprinkle brown sugar mixture over top of pie. Bake for 20 minutes more or until a knife inserted near the center comes out clean and topping is golden and bubbly. Cool on a wire rack. Cover and refrigerate within 2 hours.
I don't add the lemon peel, and I add 1/4 tsp ginger, increase the vanilla to 1 tsp, I used fresh cooked pumpkin instead of canned and I omit the topping for a regular pie. For Thanksgiving 2006 I added 3 small gala apples, sliced to the pie.