Place the eggs yolks, sugar and vanilla seeds into a bowl and whisk together until pale and light.
Add the mascarpone and whisk to combine well.
Place the coffee and Marsala into a clean bowl.
Dip a sponge finger into the coffee mixture and press into the bottom of a tumbler or sundae glass. Repeat this process, using four sponge fingers in total, to line the bottom of the glass.
Spoon some black cherries into the glass over the sponge fingers.
Add a layer of the mascarpone mixture to cover the cherries.
Repeat with a layer of black cherries and a layer of mascarpone mixture to fill the glass.
Repeat this process to make five more desserts.
To serve, smooth over the top of each tiramisu and dust each with cocoa powder.