Step 1

Place 2 tablespoons of the matcha in a mug or small shallow bowl. Pour ¼ cup of the hot water into the mug. Using a small whisk or matcha whisk, whisk to dissolve the matcha. Add the remaining ¾ cup hot water. Working one at a time, dip the ladyfingers into the matcha, holding them for 5 seconds to soak. Layer them in a 9-inch round ceramic or glass baking dish. Set aside.

Step 2

In a stand mixer fitted with the whisk (or in a bowl with a hand mixer), beat the egg whites until foamy. Set aside.

Step 3

In a small saucepan, combine 3 tablespoons of the sugar and 2 tablespoons water. Bring to a boil over medium-high heat and cook until the sugar dissolves and thickens, being careful not to caramelize the sugar, about 5 minutes. If you have a thermometer, the sugar mixture should be between 245° and 248°F (118° and 120°C).

Step 4

With the mixer on medium speed, drizzle the hot syrup into the egg whites. Whisk until stiff, glossy peaks form, about 5 minutes. Refrigerate until ready to use.

Step 5

Pour 1 inch of water into a medium saucepan and bring to a gentle simmer over medium heat. In a heatproof medium bowl (that can sit over the saucepan without touching the water), whisk together the egg yolks, rum, and remaining 3 tablespoons sugar. Set the bowl over the saucepan and whisk the egg yolk mixture until pale yellow and doubled in volume, about 5 minutes. Remove the bowl from the saucepan and let cool for 5 minutes.

Step 6

In a separate medium bowl, whisk the mascarpone cheese to loosen it. Slowly add the warmed egg yolk mixture to the mascarpone cheese. Whisk until smooth. Using a rubber spatula, fold in the whipped egg whites. Mix until smooth and just combined.

Step 7

Pour the mascarpone mixture over the ladyfingers. Cover with plastic wrap and refrigerate for 1 hour and up to overnight.

Step 8

Dust the top with the remaining 1½ teaspoons matcha before serving.

Step 9

Enjoy!