Combine the cooled coffee and coffee liqueur (if using) in a shallow bowl. Set aside.
In a large bowl, beat the mascarpone cheese, pumpkin puree, powdered sugar, pumpkin pie spice, and vanilla extract with an electric mixer until smooth and creamy, about 2 minutes.
In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the pumpkin-mascarpone mixture until fully combined but still fluffy.
Quickly dip each ladyfinger into the coffee mixture (about 2 seconds per side—don't let them get soggy!) and arrange them in a single layer in the bottom of a 9x13-inch dish.
Spread half of the pumpkin cream mixture over the ladyfingers, smoothing it into an even layer.
Repeat with another layer of coffee-dipped ladyfingers and the remaining pumpkin cream mixture.
Cover tightly with plastic wrap and refrigerate for at least 4 hours or overnight to let all those amazing flavors meld together.
Before serving, dust the top with a mixture of cocoa powder and cinnamon using a fine-mesh sieve. Cut into squares and enjoy the compliments!