Line an 8” square baking dish with plastic wrap, leaving a 3” overhang on all sides. Set pan aside.

Using a medium bowl, whisk together the egg yolks and 3 Tbsp of sugar until light yellow in color (~2-3 minutes).

{Optional} Add rum and mix until fully combined.

Add the marcarpone, pumpkin puree and pumpkin pie spice; mix until smooth. Set mixture aside.

Using an electric mixer, beat the egg whites with remaining 2 Tbsp of sugar until stiff peaks form. (~5 minutes)

Fold the whipped cream, lemon juice, and vanilla into the beaten egg whites. Then fold the egg white mixture into the mascarpone mixture. Set aside.

Pour the coffee into a shallow bowl. One at a time, dip the ladyfingers in the coffee until soaked but not soggy. Create the base layer by laying half of the ladyfingers in the prepared pan.

Spread ½ of the custard mixture over the ladyfingers.

Repeat process with remaining ladyfingers (arranged in the opposite direction) and remaining custard. Cover with plastic wrap and refrigerate at least 4 hours, or overnight.

Before serving, sprinkle crumbled gingersnap cookies on top and then dust lightly with powdered sugar.