Vegan Jaffa Cake Dessert

This pudding came about when I was pondering the injustice of there not being a vegan equivalent of trifle as (to my knowledge), no-one has ever devised an acceptable non-dairy substitute for double or whipping cream (or not in the UK anyway).  It is a bit of cheat as there is not much cooking involved but it's a good one for slinging together at the last minute as it sets quickly and mostly uses ingredients that you can find in a decent supermarket.  I was pleasantly surpised to find out that vegan jelly is easier to find than I thought.  In my research, I came across three brands that do an orange or mandarin flavour - Green's Quick-Jel, Hartley's QuickSet Jelly (not the regular variety) and Marks & Spencer's from their Terribly Clever range. I made my own vegan sponge cake base for this but you might find that your supermarket sells a ready made equivalent as part of a FreeFrom-type range (or if your dessert doesn't have to be vegan, use ready-made trifle sponges).

This makes either one big dessert (to serve 6-8 people) or 6 individual ones.  It tastes pretty good!

For the vegan sponge base:
50g non-dairy margarine
50g caster sugar
20g egg replacer
50g self-raising flour, sifted

1 small tin mandarin oranges in juice
1 quantity orange or mandarin vegan jelly (if you use Quick-Jel, you'll need both sachets)
x1 4-pack of dark chocolate flavour Alpro Soya desserts (they also do a regular chocolate flavour if you don't like dark chocolate - personally, not something that I understand - or if you're nostalgic for the flavour of that Heinz Chocolate Pudding that you had as a baby), chilled
40g good-quality dark chocolate, finely chopped

1. If you're making your own cake base, preheat the oven to 180 degrees C/Gas Mark 4.  Drain the mandarin segments of juice but don't throw the juice away (you'll need it for the jelly).
2. Beat together the margarine and caster sugar until pale, light and fluffy.  Using a metal spoon, fold in the egg replacer and sifted flour until there are no specks of flour visible.  You'll need to add a small amount of water to get the cake mixture to a soft dropping consistency.
3. Spoon the cake mixture into a prepared tin (one 7" sandwich cake tin is ideal).  I thought I'd save on washing up and put mine in fairy cake cases in a bun tin (the mixture will fill six).  Bake for around 20 minutes until the cake is golden and risen (it should spring back when you gently press it with a finger).  Leave the cake to cool on a wire rack.
4. Once cooled, break the cake into pieces and use to line your serving dish.  Arrange the drained mandarin segments over the sponge.
5. Make the jelly according to the packet instructions but use half water and half mandarin juice.  Leave it to cool slightly before pouring over the cake and fruit layer.
6. Once the jelly has cooled, place it in the fridge to chill.  Just before serving, spread the chilled chocolate soya dessert over the jelly and top with the finely chopped chocolate.