Mix the coffee and 2 tablespoons of the coffee liqueur in a shallow bowl and set aside.
Whip the cream, powdered sugar, vanilla, and 1 tablespoon of coffee liqueur until stiff peaks form.
Add mascarpone and gently mix until smooth. Do not overmix.
Quickly dip ladyfingers into the coffee mixture (1–2 seconds per side) and arrange 12 in a single layer in a 9x6.5 inch pan.
Spread half of the mascarpone mixture evenly over the ladyfingers.
Repeat with another layer of dipped ladyfingers and top with the remaining cream mixture.
Dust generously with unsweetened cocoa powder.
Cover and refrigerate for at least 4 hours or overnight for best flavor.
Slice and serve chilled. Dust with extra cocoa powder before serving.