Preheat oven to 400 degrees. Press a sheet of aluminum foil onto crust, draping over rim of pie plate. To blind-bake: Fill with dried beans or pie weights. Bake until edge of crust is firm, about 20 minutes. Remove beans and foil; let crust cool completely, and set aside.
Reduce heat to 350 degrees. Make filling: In a medium bowl, whisk together pumpkin, eggs, sugar, cinnamon, pie spice, vanilla, and salt; whisk in cream. Pour mixture into cooled crust; place pie plate on a rimmed baking sheet. Bake until filling is set, about 1 hour. Let cool on a wire rack, 1 hour; refrigerate to cool completely, about 2 hours.
Make topping: Place 3 tablespoons cold water in a small saucepan; sprinkle with gelatin, and let soften, about 5 minutes. Place pan over very low heat; stir until gelatin dissolves. Let cool slightly. In a large bowl, using an electric mixer, beat cream and sugar until very soft peaks form. While beating, slowly add gelatin mixture; continue to beat until soft peaks form.
With a rubber spatula, mound topping in center of chilled pie. Refrigerate at least 1 hour more (or up to 1 day). Sprinkle with more cinnamon before serving.