Prepare the Matcha Mixture: In a small bowl, whisk the matcha powder with 1/2 cup of the cooled green tea until smooth. Set aside.
Egg Yolks and Mascarpone Cream: In a large bowl, combine the egg yolks, sugar, and vanilla extract. Whisk until the mixture turns pale and creamy. Then, gently fold in the mascarpone cheese until well incorporated.
Whip the Cream: In a separate chilled bowl, beat the heavy cream until it forms soft peaks. Carefully fold the whipped cream into the mascarpone mixture to maintain its light texture.
Egg Whites: In another bowl, add a pinch of salt to the egg whites and beat until stiff peaks form. Gently fold the egg whites into the mascarpone mixture until evenly blended.
Assemble the Dessert: Dip each ladyfinger quickly into the remaining green tea mixed with the matcha mixture. Gently lay a row of thoroughly soaked ladyfingers at the base of your serving dish. Next, spread a layer of the mascarpone-matcha cream evenly over the ladyfingers. Repeat the layering process until you run out of ingredients, ending with a creamy top layer.
Chill: Cover the dish with plastic wrap and chill in the refrigerator for at least 3 hours or overnight. This allows the flavors to meld and the dessert to firm up beautifully.
Garnish and Serve: Before serving, dust a light layer of matcha powder over the top and garnish with fresh berries or a mint leaf if desired.