out clean from the middle of the cake and it should spring back from a touch. immediately slide a knife around the edge of each cake so that it shrinks evenly. leave to cool in the tin for 5 minutes then remove to the rack and peel off the paper.
while the sponges are baking, place the water and sugar into a small saucepan. scrape the seeds out of the pod and add both the seeds and pod to the pan. heat over a medium heat until the sugar has fully dissolved. leave to steep until needed.
whip the double cream until it holds soft peaks. split the cool sponges into two 