In a microwave-safe bowl, whisk cream and gelatin until all the gelatin is wet and the mixture looks slightly lumpy. Let mixture sit until it looks like loose cottage cheese, about 5 minutes.
Microwave gelatin mixture until the gelatin has melted, about 1 minute, whisking after 30 seconds. Whisk until smooth and syrupy and no lumps remain. (If you still see lumps, trying microwaving for 30-second increments.)
In a large microwave-safe bowl, whisk together pumpkin, sugar, maple syrup, ginger, salt, cinnamon, and nutmeg until combined. Microwave until heated to 110 degrees, about 2 minutes, stirring after 1 minute.
Immediately whisk in gelatin mixture until combined. Pour filling into crust. Gently shake pie filling so it spreads to the edges of the crust. Cool 10 minutes.
Spray a sheet of plastic wrap with nonstick spray and gently press on top of the filling. Refrigerate for at least 4 hours. Or, wrap in aluminum foil and freeze for up to 2 weeks (To serve, completely unwrap pie and thaw at room temperature for 5 hours).
To make the topping:
Using a standing mixer fit with the whisk attachment, or with an electric hand mixer, whip heavy cream, maple syrup, cinnamon, and salt on medium-low speed until foamy, about 1 minute.
Increase speed to high and whip until soft peaks form, about 1 to 3 minutes. Topping can be refrigerated for up to 24 hours. Spread topping evenly over pie before serving.
Notes
Gelatin: This helps the pie set up without the need for the usual custard mixture which is not freezer-friendly.
Pie crust:Make your own pie crust or use a store-bought crust. To make the crust in advance, make the dough, form it into a disk shape, wrap it tightly in plastic wrap and foil, and freeze for up to 2 months. To use, thaw it overnight in the refrigerator, then roll it out. If you have the space, you can roll out your pastry dough, press it into the pie pan, and freeze it, tightly wrapped in plastic. You can bake frozen pie crust straight out of the freezer without thawing.
Yield: This recipe makes 1 pie with 8 slices (or more or less, depending on how you slice it).
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Freezer: Freeze for up to two weeks. The day you need it, take it out and let it thaw on the counter. In about five hours or less, it will be room temperature and ready to eat.
Whipped cream: This recipe has its own version of a maple-cinnamon whipped cream topping, but you can make regular whipped cream if you prefer that.