Combine the ginger, turmeric, cardamom, allspice, nutmeg, black pepper and 2 teaspoons cinnamon in a small bowl. Toast 1 1/2 tablespoons of the spice mixture in a medium saucepan over medium heat, stirring, until fragrant, about 1 minute. Pour in about 2 tablespoons of the milk, whisking to combine until smooth. Gradually drizzle in the remaining milk, whisking continuously to avoid any lumps, and bring to a simmer, whisking frequently. Remove from the heat and allow to cool slightly.
Whisk together the egg yolks, granulated sugar and salt in a large saucepan, then slowly drizzle in 2/3 cup of the milk mixture while whisking continuously. (You don't want to scramble the eggs!) Turn the heat on medium and cook for a few minutes, whisking continuously, until the mixture thickens and coats the back of a spoon. Remove from the heat, then pour the mixture into a large bowl. Cover with plastic wrap, pressing it up against the surface of the custard, and let cool in the fridge for about 1 hour.
Beat the heavy cream, powdered sugar, remaining 1/2 teaspoon cinnamon and the vanilla to stiff peaks in a stand mixer fitted with a whisk or in a large bowl with an electric mixer, then set aside.
Fold the mascarpone into the cooled custard.
Working one at a time, quickly soak the ladyfingers in the remaining golden spiced mixture and use them to line the bottom of an 8-inch square pan, breaking them up if necessary. (Soak them for about 2 seconds; don't soak them too long, otherwise they'll fall apart.) Add half of the custard, spreading it out evenly with an offset spatula, followed by a layer of the whipped cream. Repeat! Using a sifter or a fine-mesh sieve, dust the top with some of the remaining spice mixture and allow to set for at least 4 hours or up to overnight.