Pie crust (see Paula Deen's for the best fresh one - graham cracker pie crust also works well)
1 15-ounce can pure pumpkin
1 14-ounce can sweetened condensed milk
1/4 cup sour cream
2 teaspoons ground cinnamon
3/4 teaspoon ground ginger
1/2 teaspoon vanilla extract
1/4 teaspoon ground allspice
2 large eggs
3/4 cup chilled whipping cream
2 tablespoons sugar
Preheat oven to 400°F. Reshape crust edge to form high-standing rim. Bake crust until browned, pressing bottom and sides of crust occasionally with back of fork, about 14 minutes. Cool crust on rack. Reduce oven temperature to 350°F.
Whisk pumpkin, condensed milk, sour cream, 1 1/2 teaspoons cinnamon, 1/2 teaspoon ginger, vanilla, and allspice in large bowl to blend. Whisk in eggs. Pour into crust (some filling may be left over).
Bake pie until filling is puffed around sides and set in center, about 55 minutes. Cool pie on rack. (Can be made ahead. Let stand at room temperature 2 hours, or cover and chill overnight.)
Beat whipping cream, sugar, 1/2 teaspoon cinnamon, and 1/4 teaspoon ginger in bowl until peaks form. Spoon large dollops around edge of pie and serve.