1. Brew and cool the espresso. Pour into a wide shallow bowl and cool completely to room temperature or refrigerate. Stir in the dry Marsala (if using) and set aside. Do not skip this step — warm espresso will over-soak the ladyfingers.

2. Prep the springform pan. Line the bottom and the sides with parchment paper held in place with small dabs of butter which will act like "glue”.

3. Whip the egg yolks. Place 5 egg yolks in a stand mixer bowl with the whisk attachment. Whip on high for 5 to 7 minutes until pale, thick, and holding ribbons. Keep the mixer running while you make the syrup.

4. Make the sugar syrup. Combine 130g sugar and 40ml water in a small heavy-bottomed saucepan. Stir once, place over medium heat, and do not stir again. Cook to 250°F/121°C (approximately 6 to 8 minutes from when it starts to simmer). Without a thermometer: the syrup is ready when the bubbles shift from large and lazy to small, fast, and vigorous, and the syrup looks thick, glassy, and nearly transparent. Test at the 6½ minute mark — drop a small amount into cold water. If it forms a firm but pliable ball, it's ready. If it dissolves, keep going. If it snaps, it's gone too far.

5. Make the pâte à bombe. Reduce the mixer to medium speed. Pour the hot syrup in a slow, thin, steady stream down the inside wall of the bowl, never directly onto the whisk. Add the 1/8 tsp kosher salt immediately. Increase to high speed and whip 10 to 12 minutes or until the bowl is completely cool to the touch and the mixture is pale, thick, and holds a ribbon. The pâte à bombe must be fully cooled before cold mascarpone is added or the cream will be runny.

6. Add the mascarpone. Briefly loosen the cold mascarpone with a spatula in a separate bowl. Reduce the mixer to its lowest speed. Add mascarpone to the pâte à bombe one or two heaping spoonfuls at a time, waiting for each addition to incorporate before adding the next. Mix only until smooth and streak-free. Stop immediately.

7. Fold in the whipped cream. In a separate cold bowl, whip the cold heavy cream to stiff peaks. Fold into the mascarpone mixture in two or three additions using slow bottom-to-top movements. Stop as soon as no white streaks remain. The finished cream should hold its shape on a spatula and look smooth and glossy.

8. First layer — flower scallop edged method. Open one inner pack of savoiardi. Cut 6 ladyfingers in half to be used around the perimeter. Working one at a time, dip each piece in the espresso for no more than 1.5 to 2 seconds per side. Add 3 whole ladyfingers across the center of the pan. Work outward, fitting halved pieces and cut scraps around them, and tuck the rounded ends around the perimeter with curved sides facing outward against the parchment. Fill every gap. No empty spaces. Sprinkle any sugar and crumbs from the pack directly over the layer.

9. Build the layers. Spread one-third of the mascarpone cream evenly over the first ladyfinger layer. Dip and arrange a second layer of ladyfingers over the cream, rotating them 90 degrees from the first layer. Spread another third of the cream. Add a third layer of dipped ladyfingers, then top with the final third of cream, smoothed completely flat. You will have 3 ladyfinger layers and 3 cream layers.

10. Refrigerate. Cover the pan without letting the wrap touch the cream surface. Refrigerate overnight minimum. One to two days ahead is better still.

11. Unmold, dust, and serve. Just before serving, add optional chopped dark chocolate (78% or higher), then dust generously with unsweetened cocoa powder through a fine mesh sieve held 8 to 12 inches above the surface. Remove the springform ring, peel away the parchment, and slice with a sharp non-serrated knife, wiping the blade clean between cuts. Serve cold with a small pitcher of cold espresso on the side.