In a heatproof bowl (or the top of a double boiler), whisk together 4 egg yolks and 3 tablespoons granulated sugar until the mixture is pale and slightly thickened (about 1–2 minutes). Place the bowl over barely simmering water (water should not touch the bowl) and continue whisking for 4–6 minutes until the mixture registers 160°F (71°C) or is noticeably thicker and ribbons off the whisk. Remove from heat and let cool for 5 minutes.

Incorporate mascarpone

When the yolk mixture is warm (not hot), fold in 16 oz mascarpone cheese in two additions using a spatula until smooth and lump-free. Add 1 teaspoon vanilla extract and a pinch of salt; fold gently to combine. Chill briefly if the mixture feels too loose (5–10 minutes).

Whip cream and combine

In a separate chilled bowl, whip 1 cup cold heavy cream to soft peaks. Gently fold one-third of the whipped cream into the mascarpone mixture to loosen it, then fold in the remaining whipped cream in two additions until homogeneous and light. Do not overfold — stop when the mixture is smooth and spreadable.

Coffee Soak & Assembly

Prepare coffee soak

Combine 1 cup cooled strong brewed coffee or espresso with 3 tablespoons coffee liqueur (optional) in a shallow dish. Taste and adjust: it should be strong and slightly sweetened by the liqueur but not syrupy.

Assemble first layer

Quickly dip each ladyfinger (about 24 total) into the coffee mixture for 1–2 seconds per side — do not soak them until soggy; they should be moistened but still hold shape. Arrange a single layer of dipped ladyfingers, seam side down, to cover the bottom of a 9x9-inch (or similar) dish.

Add mascarpone layer

Spread about half of the mascarpone filling evenly over the first layer of ladyfingers, smoothing the top with an offset spatula. Ensure edges are covered.

Second layer and finish

Repeat: dip remaining ladyfingers quickly in coffee and arrange a second layer on top of the mascarpone. Spread the remaining mascarpone filling evenly over the second ladyfinger layer. Smooth the surface.

Chill and serve

Cover the assembled tiramisu with plastic wrap and refrigerate for at least 4 hours, preferably 8–12 hours or overnight, to let flavors meld and for the texture to set. Just before serving, dust the top with 2 tablespoons unsweetened cocoa powder using a fine sieve and optionally grate 0.5 oz dark chocolate over the cocoa. Cut into portions and serve chilled.