In a large bowl, whip the heavy cream until stiff peaks form. Set aside.
In a separate bowl, beat the softened mascarpone cheese and granulated sugar until smooth and creamy.
Gently fold the whipped cream into the mascarpone mixture until well combined.
In a small bowl, whisk together the matcha powder and hot water until smooth. Add the matcha liqueur or coffee liqueur, if using.
Quickly dip each ladyfinger into the matcha mixture and arrange them in a single layer at the bottom of a 8x8 inch baking dish.
Spread half of the mascarpone cream mixture over the ladyfingers.
Repeat the layers with the remaining ladyfingers and mascarpone cream.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or preferably overnight.
Before serving, dust the top with additional matcha powder.
Cut into squares and serve chilled.
Optional Tips: For a stronger matcha flavor, increase the amount of matcha powder. If matcha liqueur is unavailable, coffee liqueur can be used as a substitute, or it can be omitted entirely. For a softer texture, soak the ladyfingers slightly longer, but be careful not to over-saturate them.