Step 1: Prepare the Spiced Egg Base
Gather all ingredients. Fill a large saucepan with a few inches of water and bring to a boil over medium heat. Place a heatproof bowl over the saucepan, ensuring the bottom does not touch the water. Add the egg yolks and sugar to the bowl. Whisk continuously for 4 to 5 minutes until the mixture is smooth and the sugar is dissolved.

Step 2: Flavor and Chill the Base
Immediately remove the bowl from the heat. Whisk in the molasses, cinnamon, ginger, allspice, nutmeg, salt, and vanilla extract. Transfer the mixture to a clean bowl, cover it, and place it in the refrigerator to cool completely for about 25 minutes.

Step 3: Create the Mascarpone Filling
Use an electric mixer to beat the softened mascarpone cheese into the chilled egg yolk mixture on medium speed until the entire mixture is smooth and uniform. Be careful not to over-mix.

Step 4: Fold in the Cream
In a separate, clean bowl, whip 2 cups of the whipping cream to stiff peaks. Gently fold this whipped cream into the mascarpone mixture until just combined. Set this main filling aside.

Step 5: Build the First Layer
Dunk one third (about 16) of the crisp ladyfingers, one at a time, into the cooled strong brewed coffee for just a quick second or two. Line the bottom of a 9×13-inch baking dish with the soaked ladyfingers, cutting them if necessary for an even layer. Top this layer with 2 cups of the mascarpone mixture, spreading it out evenly.

Step 6: Complete the Layers
Repeat the process with another layer of coffee-dipped ladyfingers and another layer of the remaining main mascarpone mixture. You will use the final portion of ladyfingers to create three total layers of ladyfingers. Top this final ladyfinger layer with 2 cups of the main mascarpone filling, leaving about 1 1/2 cups of the filling mixture remaining.

Step 7: Whip and Top
Whip the remaining 1/2 cup of whipping cream to stiff peaks. Gently fold this newly whipped cream into the remaining 1 1/2 cups of mascarpone mixture. Spread this final, lighter mixture evenly over the top layer of the tiramisu.

Step 8: Chill and Garnish
Cover the dish and chill the tiramisu for at least 4 hours, or ideally overnight, for the best flavor and texture. Before serving, finely crush the 1 to 2 gingersnap cookies and lightly sprinkle the crumbs over the top.