Step 1: Prepare the Coffee Soak. Pour the cooled espresso or strong coffee into a shallow bowl. If you prefer a sweeter base, you can stir in a teaspoon of sugar while the coffee is still warm, then let it cool completely before using.
Step 2: Whip the Heavy Cream. In a large chilled bowl, beat the heavy whipping cream with 1/4 cup of powdered sugar and the vanilla extract. Use a hand mixer or stand mixer to beat until stiff peaks form. Set this aside in the refrigerator to keep it cold.
Step 3: Mix the Pumpkin Base. In a separate medium bowl, combine the softened mascarpone cheese, pumpkin puree, the remaining 1/4 cup of powdered sugar, and the pumpkin pie spice. Mix until the texture is smooth and well-combined, ensuring there are no lumps of cheese.
Step 4: Fold the Creams Together. Gently fold about one-third of the whipped cream into the pumpkin mascarpone mixture to lighten it up. Then, fold in the rest of the whipped cream carefully. Use a spatula and a light hand to keep the mixture airy and fluffy.
Step 5: Layer the Cups. Break the ladyfingers into pieces that fit your serving cups. Quickly dip each piece into the coffee—about 1 second per side—and place a layer at the bottom of each cup. Top with a generous dollop of the pumpkin cream. Repeat with another layer of dipped ladyfingers and a final layer of cream.
Step 6: Chill and Garnish. Cover the cups with plastic wrap and refrigerate for at least 4 hours, or ideally overnight. This allows the ladyfingers to soften and the flavors to meld. Just before serving, dust the tops generously with cocoa powder through a fine-mesh sieve.