Icebox Pumpkin-Mousse Pie

Make the crust: Preheat oven to 325 degrees. In a food processor, process wafers and brown sugar until finely ground. With machine running, slowly add butter and process until mixture resembles wet sand. Firmly press crumb mixture into bottom and up sides of a 9-inch pie plate. Bake until crust is dry and set, 10 to 12 minutes. Let cool completely in plate on a wire rack.

Make the filling: In a clean food processor, process pumpkin puree, cream cheese, brown sugar, cinnamon, and nutmeg until smooth, scraping down sides as needed. With machine running, add maple syrup in a slow, steady stream. In a large bowl, using an electric mixer, beat cream on high until stiff peaks form, 3 minutes. With a rubber spatula, gently fold pumpkin mixture into whipped cream. Spoon filling into crust and refrigerate until set, 3 hours (or up to 1 day).

Make the topping: In a medium bowl, using an electric mixer, beat cream and confectioners' sugar on high until stiff peaks form, 3 minutes. With spatula, mound topping over pie and serve immediately.