Start by preheating the oven to 180 degrees celsius. Then grease three 24 centimeter by 34 centimeter rimmed baking trays. Line with baking paper allowing the sides to overhang.
To make the cake, place the egg yolks and sugar in a large bowl of an electric mixer and whisk until pale and creamy. Then stir in the flour and cocoa powder. Next add the egg whites to a clean bowl of an electric mixer, whisk until soft peaks form, then add 1/3 of the egg white to the cocoa mixture. Stir to combine. Fold in the remaining egg whites until well combined.
Spoon the cake mixture evenly among the prepared pans and use the back of a metal spoon to smooth the surface. Bake swapping the trays halfway through cooking for 15 minutes or until dry to touch. Place three large baking sheets of baking paper on a clean work surface. Dust heavily with extra cocoa powder. Turn one cake onto one sheet of the prepared baking paper. Carefully remove the top sheet of baking paper. Repeat with the remaining cakes then set aside for 20 minutes to cool.
To make the mascarpone cream place the coffee and boiling water in a small bow,l stir until the coffee dissolves. Place the cream cheese and sugar in a large bowl of an electric mixer and beat until smooth. Add the coffee mixture and beat until smooth and well combined. Add the mascarpone and wine and beat until soft peaks form.
Use a large serrated knife to trim the edges of each cake, then cut each cake in half lengthwise. Thinly spread some of the mascarpone mixture evenly over one cake half, starting from one short end roll up the cake to enclose the filling. Spread another cake half with a little more of the mascarpone mixture. Top with the rolled cake seam side down. Roll up the cake half to enclose the rolled cake repeat the rolling with the remaining cake halves and half the mascarpone mixture finishing with a cake half turn the cake roll onto one flat end and place on a serving plate.
Spread half the remaining mascarpone mixture over the top and the sides of the cake. Place the remaining mascarpone mixture in a piping bag fitted with a one centimetre plain nozzle and pipe over the top of the cake. To finish, dust the cake with cocoa powder. This vertical tiramisu cake will add some wow factor to any celebration.