Put the leaves from 2 tea bags, 90g sugar, 300ml water and the zest from 1 clementine and 100ml juice in a saucepan set over a high heat. Bring to the boil, whisking occasionally, then remove from the heat and infuse for 10 minutes. Pass through a fine sieve into a clean pan (discard the tea leaves).
Return to the heat. Once boiling, remove from the heat and whisk in the gelatine until dissolved. Pour the liquid into a shallow non-stick tin, about 12cm x 22cm (no smaller) and chill in the fridge for 2 hours until set.
Meanwhile, preheat the oven to 180°C, gas mark 4. Grease a 12-hole shallow muffin tin.
Put the eggs and the rest of the sugar in a bowl. Beat with an electric hand whisk for 2 minutes until thick and pale. Sift in the flour and gently fold in with the remaining clementine zest, leaves from the final tea bag and a pinch of salt. Divide the mixture among the holes. Bake for 8-10 minutes, or until a skewer inserted into the centre comes out clean. Cool in the tin for 10 minutes then invert onto a wire rack to cool completely.
Melt the dark chocolate in a heatproof bowl set over a pan of barely simmering water. Leave to cool for 10 minutes.
Use a cutter to stamp out 12 x 4cm rounds from the jelly. Place a round on top of each cake and drizzle with melted chocolate to cover. Leave to set at room temperature before serving the jaffa cakes.