Make the mascarpone filling: in the bowl of an electric mixer fitted with the whip attachment (or in a large bowl if using a hand mixer), whip the cream, sugar, cocoa powder, vanilla, and fine sea salt to medium peaks.

Add the mascarpone cheese and mix on low speed until evenly incorporated. Finally, add the warm chocolate and quickly mix to combine. If needed, fold the mixture a few times by hand to make sure it’s totally smooth, evenly combined, and thick. Set aside.

Make the soaking mixture: put the cooled hot chocolate or chocolate milk into a shallow bowl. Have ready a 9 x 13 inch / 23 x 33 cm rectangular baking pan.

Assemble the tiramisu: working with one at a time, dip a ladyfinger briefly into the soaking mixture, and transfer it to the baking pan. As you place them, you can place them as close together as possible - or very slightly overlap them to ensure you get full coverage on the bottom of the pan. You should use half of the ladyfingers to fill the base of the pan.

Scoop half of the chocolate mascarpone filling on top of the ladyfingers, and spread into an even layer.

Repeat the dipping process, dipping the remaining ladyfingers briefly into the soaking mixture, and arranging them into an even layer fully covering the mascarpone filling.

Spoon the remaining mascarpone filling on top, and spread into an even layer. You can make this layer totally smooth, or create texture intentionally (such as stripes with an offset spatula).

Sift the cocoa powder, or sprinkle the chocolate shavings or curls evenly over the surface, trying to get even coverage. Refrigerate the tiramisu for at least 4 hours (and up to 24 hours) before serving.