In the bowl of your stand mixer, or in a large bowl with a hand mixer, whip the cream until the cream reaches stiff peaks. Set aside.
In another bowl, mix the mascarpone cheese, powdered sugar and instant coffee on low speed until combined (use your stand mixer or hand mixer, or a whisk by hand).
Add the pumpkin puree, pumpkin pie spice, and vanilla, and mix to combine.
Fold the whipping cream into the mascarpone mixture gently just until no streaks of whipping cream are visible. Be very gentle with this - you don't want to deflate the whipping cream.
Set the cream mixture aside for a minute and dip each of the ladyfingers into the coffee briefly, lining the bottom of a large rectangular baking dish (around 9-inch by 13-inch in size) with the soaked ladyfingers.
Smooth half the cream mixture over the layer of coffee-soaked ladyfingers and smooth out the top.
Add one more layer of coffee-soaked ladyfingers over the cream layer, and add the other half of the cream mixture, smoothing out the top.
Refrigerate uncovered for about 6 hours or overnight.
Before slicing and serving, sprinkle the top with cinnamon.