In a small bowl, combine the coffee and liqueur; set aside.
In a medium bowl, beat the mascarpone cheese and confectioners' sugar until smooth.
Place one cake layer upside down on a serving platter and prick the top several times with a fork. Pour half of the coffee mixture slowly over the top, allowing it to absorb into the cake. Spread the cheese mixture evenly over the layer, then place the second cake layer right side up over the cheese mixture. Prick the top of the second cake layer several times with a fork and pour the remaining coffee mixture over the top.