Serves: Makes two 0.5L Kilner jars of Tiramisu - enough to feed 6 people
Beat together the mascarpone cheese, condensed milk and vanilla extract until light and fluffy.
One at a time, soak the sponge fingers in the cold espresso (a couple of seconds will do) and make a single layer into a 0.5L Kilner jar. You might need to break them into smaller pieces to make sure the entire bottom of the jar is covered.
Next, spoon in a generous amount of the cream mixture, covering all the biscuits. Next, grate over some dark chocolate.
Repeat the process another three times until you've used up all the biscuits, espresso and cream. Finish with a dusting of cocoa powder.
Place in the fridge a couple of hours before serving to make sure the biscuits soak in all of the espresso and some of the cream mixture. You can make this up to two days in advance of serving and it will keep in the fridge for 3 days.