Preheat food processor to high setting. Add gingersnap cookies and pulse until finely crushed. Combine crushed cookies with melted butter and salt, mix until moistened, then press into 9-inch pie plate. Chill for at least 30 minutes.

In a stand mixer, beat room temperature cream cheese and powdered sugar on medium speed until smooth. Gradually add pumpkin puree, vanilla extract, and pumpkin pie spice, mixing until combined.

In a chilled mixing bowl, pour cold whipping cream and whip on medium-high speed until soft peaks form, about 3-5 minutes.

Gently fold whipped cream into the pumpkin mixture using a spatula, maintaining the airy consistency.

Transfer pumpkin mousse into the chilled crust and smooth the top. Cover with plastic wrap and refrigerate for at least 3 hours or overnight.

Whip additional cold heavy cream with powdered sugar, maple syrup, and ground cinnamon until soft-stiff peaks form. Spread over top of chilled pie.