Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, grease and line a swiss roll tin or baking tray with a lip (I used a Wilton Non-Stick Cookie Pan 15.25 x 10.25 Inches)
Whisk together the eggs and caster sugar with an electric hand mixer, whisk for 5-8 minutes until the mixture grows in size and is pale and thick
Sieve the self raising flour and cocoa powder into a separate bowl, then gently fold them into the whipped egg mixture
Melt the butter either in the microwave or in a small pan on a low heat. Fold it into the mixture
Pour the mixture into the tin and spread out gently so it reaches all the corner and edges
Bake the sponge for 12 minutes or until risen and it springs back when you gently press your finger into it. Turn it out onto a cooling rack to cool down completely
Once fully cool, cut out discs using a 7cm diameter cutter
Whip up the double cream with the vanilla extract and pipe a ring of it onto the bottom half of 6 of the cakes rounds
Fill the centre with the cherry jam
Put the undecorated rounds of cake on top of the cream and jam. Pipe on more cream, sprinkle over some grated dark chocolate and place a cherry in the middle
Store leftovers in an airtight container in the fridge and eat within 2 days