Lightly oil a 9-inch springform pan. Cut 4-5 strips of parchment paper into 12" x 2" strips and lay them crisscross along the bottom of the pan so that the sides hang out when the pan is clasped.

In the bowl of a stand mixer, beat the whipping cream and sugar together until light and stiff peaks form. Scoop into another bowl and set aside.

Beat the mascarpone in the same bowl of the stand mixer until softened and smooth. Add the pumpkin and pumpkin pie spice, mixing well. Gently fold in two-thirds of the whipped cream mixture until totally incorporated.

Mix the coffee and pumpkin liqueur in a medium-sized bowl.

Cut the ladyfinger cookies in half. Quickly dip each side of the cookie in the coffee and liqueur mixture. Stand the cut ladyfingers upright to line the sides of the pan. Continue dipping and arrange the ladyfingers on the bottom of the pan, cutting the cookies to fit.

Spoon half of the pumpkin filling over the ladyfingers, then add another layer of dipped ladyfingers on top of the pumpkin mixture. Dollop the rest of the mixture on top and smooth evenly with the back of a spoon.

Top with the reserved whipped cream mixture, spreading evenly. Sprinkle with crumbled gingersnaps. Cover carefully and chill for 8 to 24 hours.

To un-mold, unlock the clasp and carefully jiggle the mold. Use a knife if needed to separate from the pan. Using the parchment paper strips, move the tiramisu from the bottom of the springform pan onto a serving platter. Carefully slide the parchment strips from the bottom, cut into pie-shaped wedges, and serve.