Combine the mascarpone, pumpkin puree, brown sugar, ¼ cup granulated sugar, salt, cinnamon, ginger, cloves, nutmeg and heavy cream in a large bowl.
Use an electric mixer to whip the mixture until it forms medium-stiff peaks. When you lift the mixer out of the bowl, it should form peaks that gently flop over but remain intact and don't melt back into the bowl. Don't overmix.
In a small bowl, mix together the remaining 1 tablespoon of sugar with the coffee and optional bourbon or rum until the sugar is dissolved.
Dip the ladyfingers in the coffee on both sides, then line the bottom of a 9-inch springform pan. You can break them apart as needed to fit.
Top with ¼ of the pumpkin mousse and spread it into an even layer.
Repeat with the remaining ladyfingers and mousse to make 3 more layers, ending with the pumpkin mousse. You might have some ladyfingers leftover.
Cover and refrigerate for at least 8 hours (overnight is best).
When ready to serve, release the sides of the pan and carefully unmold.
Sprinkle with the roasted and salted pumpkin seeds, slice into wedges and serve.