Lightly oil a 9-inch springform pan . Cut 4-5 strips of parchment paper into strip about 12’ X 2” and lay them criss cross 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 cheese in the same bowl of the stand mixer until softened and smooth. Add the pumpkin and pumpkin pie spice and mix well. Gently fold in ⅔ of the whip cream mixture until totally incorporated.
Mix the coffee and pumpkin liqueur in a medium size bowl.
To assemble, cut the lady finger 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 lady fingers 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 ginger snaps. Cover carefully and chill for 8 to 24 hours.
To un-mold, unlock 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 spring-form pan onto a serving platter. Carefully slide the parchment strips from the bottom, cut into pie shaped wedges and serve.