Line a 9 inch pie plate with 1 9-inch pie crust. Roll edges under and create a scalloped pattern.
In a large bowl, combine the 15 ounces pumpkin puree, 2/3 cup granulated sugar, 2 large eggs, and 1 tablespoon pumpkin pie spice until smooth. Pour the mixture into the pie dough and level it with the back of the spoon.
Wash and dry the bowl, and then combine the 1/2 cup light corn syrup, 1/2 cup granulated sugar, 2 large eggs, melted 3 tablespoons butter, 1/2 teaspoon vanilla extract and 1 cup pecan halves. Gently pour over the pumpkin mixture. If desired, place the pecans in a symmetrical pattern.
Cover the crust loosely with aluminum foil or a pie shield to keep it from browning too much.
Bake in preheated 425°F oven for 15 minutes. Without opening the door, reduce heat to 350°F. Bake an additional 40-45 minutes until crust is golden brown. Turn oven off and crack oven door. Allow pie to sit in open oven for about 15 minutes before removing.
Cool on a wire rack for 1 hour. Cover with plastic wrap and refrigerate overnight. Serve with whipped cream if desired.