Brew 1 1/2 cups of espresso or very strong coffee and let it cool to room temperature. While still warm, stir in 3–4 tablespoons granulated sugar until dissolved. Add 1 teaspoon vanilla extract and 2–3 tablespoons Marsala wine, rum, brandy, or coffee liqueur if using. Set aside to cool completely so it doesn’t break down the ladyfingers.

Set out a 9×13-inch glass or ceramic baking dish. You can also use a smaller 8×8-inch pan for a taller tiramisu, though you may have a few extra ladyfingers.

In a medium heatproof bowl, whisk the 3 egg yolks and 1/2 cup granulated sugar together until the mixture becomes pale, thick, and ribbons off the whisk, about 2–3 minutes. A hand mixer on medium speed works well for this.

Set the bowl with the yolk mixture over a small pot of gently simmering water, making sure the bottom of the bowl does not touch the water. Whisk constantly for 5–7 minutes, until the mixture is warm, slightly thicker, and the sugar is fully dissolved. Remove from the heat and let cool to just warm or room temperature. For faster cooling, spread the mixture in a shallow bowl.

In a separate bowl, add the cold mascarpone cheese. Using a hand mixer on low speed, beat for about 30 seconds, just until loosened and smooth. Do not overbeat or the mascarpone can turn grainy.

Once the yolk mixture has cooled, gently fold it into the mascarpone cheese with a spatula until smooth and combined. If you see a few small lumps, briefly whisk on low speed, but avoid overmixing so the mascarpone stays silky.

In a clean, chilled bowl, combine the cold heavy cream, 1 teaspoon vanilla extract, and a pinch of fine sea salt. Beat on medium-high speed until the cream reaches medium-stiff peaks: it should hold its shape but still look smooth and soft, not clumpy.

Gently fold the whipped cream into the mascarpone-yolk mixture in 2–3 additions. Use slow, sweeping motions from the bottom of the bowl to the top to keep the mixture light and fluffy. The result should be a smooth, airy mascarpone cream filling.

Pour the cooled coffee mixture into a shallow dish. Working with one or two ladyfingers at a time, dip each side very quickly—about 1–2 seconds per side. The ladyfingers should absorb some coffee but remain firm enough to handle. Arrange the dipped ladyfingers in a snug single layer on the bottom of the baking dish. If your ladyfingers are especially dry and thick, you may need a slightly longer dip, but avoid oversoaking to prevent a soggy dessert.

Spread about half of the mascarpone cream evenly over the first layer of coffee-soaked ladyfingers. Use an offset spatula or the back of a spoon to smooth the surface.

Create a second layer of dipped ladyfingers on top of the cream, again placing them snugly in the dish. Spread the remaining mascarpone cream over the top, smoothing it into an even layer.

Cover the dish tightly with plastic wrap and refrigerate for at least 6 hours, preferably 8–12 hours or overnight. This chilling time allows the flavors to meld and the ladyfingers to soften into a cake-like texture.

Just before serving, use a fine-mesh sieve to dust the top of the tiramisu with an even layer of unsweetened cocoa powder. Add dark chocolate shavings or curls on top if desired.

Using a sharp knife, cut the tiramisu into neat squares. Use a small spatula to lift out each piece. Serve chilled; you can add an extra sprinkle of cocoa or a few coffee beans for presentation.