Brûléed White Chocolate Amaretti Pumpkin Pie

For the crust: Mix crushed cookies and melted butter until all the crumbs are moistened. Press evenly into a 9- to 10- inch pie pan. For the filing: In a large mixing bowl, whisk together pumpkin, eggs, granulated sugar, cornstarch, salt, and spices until smooth. Whisk in heavy cream and amaretto or almond extract until mixture is uniform in color. Melt white chocolate in a double boiler, then stir into pie filling. Place the pie pan on a baking sheet. Pour filling into the crust. Bake at 425 degrees F for 15 minutes. Reduce heat to 350 degrees F and bake for another 50 to 60 minutes, until edges are set and center jiggles slightly when you tap the side of the pan. Turn off oven, prop door open with a wooden spoon, and allow to cool in the oven for 1 hour. Transfer to a wire rack to cool completely before topping. If not serving immediately, cover and refrigerate pie. For the topping: When ready to serve, sprinkle granulated sugar evenly over top of pie, then use a kitchen torch to brûlée the top. Sprinkle edges with slivered almonds.