1. Preheat the oven to 325˚F (160°C). Line cupcake pans with paper liners. Add milk to a small saucepan. Scrape the seeds from the vanilla bean into the pan and add the scraped pod to the pan as well. Heat over medium heat just until bubbles appear around the edge of the pan. Remove from the heat and whisk in the butter until melted. Let stand 15 minutes. Remove the vanilla bean pod and discard (or rinse and save for another use). Combine the sifted cake flour, baking powder, and salt in a bowl. Set aside.

2. In a large (metal) bowl, combine the eggs and additional yolks with the sugar. Whisk lightly to blend. Set the bowl over an inch or two of simmering water and heat, whisking occasionally, until the mixture is warm and the sugar is dissolved (about 6 min). Take the bowl off of the heat and whisk on high speed until the mixture is pale yellow and fluffy, and able to hold a ribbon when the whisk is lifted.

3. Gently fold the dry ingredients into the egg mixture in two to three additions. Stir 3/4 cup of the batter into the milk mixture to thicken, then fold the milk mixture into the batter just until evenly incorporated. Divide the batter between the prepared liners, filling them about three-quarters full. Bake about 18-20 min until the cupcakes are lightly golden (I recommend to bake all cupcakes at once. The air inside the batter will emanate if you let it stand too long). Transfer pans to wire racks to cool slightly before removing from the pans.

4. To make the soaking sauce, combine the hot espresso, Kahlua (Amaretto) and sugar. Stir until the sugar is dissolved. Place the warm cupcakes on a wire rack and place a baking sheet underneath to catch dripping liquid. Use a pastry brush to brush the liquid onto the tops of the cupcakes, repeat until the syrup is used up (about four or five cycles of brushing). If necessary, poke each cupcake a few times with a wooden skewer to help the syrup soak in. Let the cupcakes cool completely before frosting.

5. For the frosting add the heavy cream to a bowl and whip on high speed until stiff peaks form. Be careful not to over beat. In another mixer bowl combine the mascarpone and confectioners sugar and beat with the paddle attachment on medium-high speed until smooth and fluffy (about 2 min). Fold about a third of the whipped cream into the mascarpone mixture with a spatula to lighten. Gently fold in the remaining whipped cream until evenly incorporated.

6. Transfer the frosting to a pastry bag fitted with a plain round (not too big) tip. Pipe small drops of frosting on top of each cupcake for a typical tiramisù look. Refrigerate until ready to serve. Just before serving, dust the cupcakes with unsweetened cocoa powder.