Giant Jaffa Cake for a 35 year old

When I asked Liam what kind of birthday cake he wanted, he decided that a giant jaffa cake was the only way forward for a boy of his advanced years. In the true spirit of experimentation I decided to give it a go. I've lost my notes so I'm writing this from memory - hopefully the amounts aren't too far off.
For the sponge:

• 110g butter
• 110g caster sugar
• 2 large eggs
• 110g self raising flour

For the jelly:

• 1 packet orange jelly (I used Hartleys which equals 135g of jelly cubes)
• 100ml orange juice

Topping:

• 1 bar of dark chocolate

Firstly, make up the jelly by chopping the cubes into a microwwave safe jug, and add the orange juice. Microwave on full until the jelly has melted, then stir well.  Fortunately I had a perfectly sized plate with a sunken area the size of my cake tin.With the benefit of hindsight I will offer the following advice: put clingfilm onto the plate before you pour on the jelly to set. Getting mine off after was nearly impossible!

I used Delia's Victoria Sponge recipe, but for some reason I am rubbish and it ended up denser than hers: Delia's makes two pieces to sandwich together, mine only made one! So, follow her instructions for the sponge. If you are better cook than me, you'll end up with an extra spare cake!

Once the cake has cooled, peel off the jelly and add to the top. Then, heat the chocolate in a double boiler, let cool slightly but not harden, then pour over the cake. I haven't put an amount as I clearly used way too much with about 190g. One 100g bar would probably do it.

Let the chocolate harden in the fridge, then try not to eat it all at once.