In a mixing bowl, combine the pumpkin puree, heavy cream, powdered sugar, vanilla extract, and pumpkin pie spice. Whip the mixture until it forms soft peaks.
In serving glasses or bowls, layer the crushed ginger snap cookies at the bottom.
Add a layer of the pumpkin mixture over the cookies, followed by a drizzle of caramel sauce.
Repeat the layers until the glasses are filled, finishing with a layer of the pumpkin mixture on top.
Drizzle additional caramel sauce over the top and sprinkle with chopped pecans if desired.
Chill the trifles in the refrigerator for at least 1 hour before serving to allow the flavors to meld.
Just before serving, top with a dollop of whipped cream if desired.