In a large bowl, whisk egg yolks and 1/2 cup sugar until thick and pale, about 3-4 minutes. The mixture should fall in ribbons when lifted.

Add mascarpone to the egg mixture and whisk until smooth and completely combined. Set aside.

In a separate bowl, whip heavy cream with remaining 1/4 cup sugar until soft peaks form. Don't overwhip.

Gently fold the whipped cream into the mascarpone mixture in three additions, being careful not to deflate the mixture.

Combine cooled espresso and Marsala wine in a shallow dish.

Quickly dip each ladyfinger into the coffee mixture, turning once, and arrange in a single layer in a 9x13 inch dish or 8x8 inch square dish for thicker layers.

Spread half of the mascarpone mixture over the ladyfingers, smoothing with an offset spatula.

Repeat with another layer of dipped ladyfingers and remaining mascarpone mixture.

Cover tightly with plastic wrap and refrigerate for at least 4 hours, preferably overnight.

Before serving, dust generously with cocoa powder using a fine-mesh sieve. Garnish with grated chocolate if desired.