Prepare the espresso and allow it to cool.
In a large bowl, combine mascarpone cheese, powdered sugar, and heavy cream.
Add in the cooled espresso and coffee liqueur, mixing until smooth.
Chill the mixture in the refrigerator for 30 minutes.
Once chilled, scoop the mixture and roll into balls.
Melt the chocolate chips in a microwave or double boiler.
Dip the truffles into the melted chocolate and let them set.
Dust the set truffles with cocoa powder.
Store the truffles in the refrigerator until serving.