Prepare the Espresso Mixture: Brew the espresso or coffee, let it cool, and mix in coffee liqueur if desired.
Make the Ice Cream Base: In a saucepan, combine heavy cream and milk, and heat until steaming but not boiling.
Whisk Egg Yolks and Sugar: In a bowl, whisk egg yolks and sugar until pale and thickened.
Temper the Eggs: Slowly add warm cream mixture to the egg yolks while whisking, then combine everything back into the saucepan.
Cook the Custard: Cook over low heat until it thickens enough to coat the back of a spoon.
Add Mascarpone and Espresso: Remove from heat and whisk in mascarpone cheese, espresso, vanilla, and salt.
Chill the Mixture: Allow the mixture to cool to room temperature, then refrigerate for 4+ hours.
Churn the Ice Cream: Pour the chilled mixture into an ice cream maker and churn until soft-serve consistency.
Add Ladyfingers: Fold in broken ladyfinger pieces gently.
Freeze & Serve: Transfer to an airtight container, freeze for at least 3 hours, and garnish with cocoa powder and chocolate shavings before serving.