First, make the orange jelly. Put the jelly cubes and marmalade (if using) in a medium heatproof bowl. Pour in the orange juice and 100ml boiling water, then stir until the jelly cubes have dissolved. Pour the mix into a shallow baking tray (ours was 25 x 20cm) lined with cling film – it should come about 1/2cm up the side. Chill for 2 hrs or overnight until set.

Heat the oven to 180C/160C fan/gas 4 and butter a shallow 12-hole cupcake tin. Tip the egg and sugar into a bowl and beat with an electric whisk for 5 mins until pale and fluffy. Or, do this in a stand mixer. Sift over the flour, add the orange zest and fold gently until there are no more pockets of flour. Spoon 1 tbsp into each hole of the tin and gently spread to the edges using the back of the spoon. Bake for 8-9 mins until the sponge is golden and a skewer comes out clean. Cool in the tin for 2 mins, then transfer to a wire rack to cool completely.

Invert the set jelly onto a board, remove the cling film and stamp out discs using a 5cm round cutter. Flip the sponges over so the flat side is facing up, then top each with a jelly disc. Tip the chocolate into a heatproof bowl and melt in short bursts in the microwave, or set the bowl over a pan of simmering water ensuring the bowl doesn’t touch the water. Set aside to cool slightly for 10-15 minutes, stirring occasionally, before spooning onto the jaffa cakes. Spoon 1-2 tsp of the melted chocolate over each disc of jelly, spreading it gently to cover. Leave to set for 2-3 mins, then gently press the tines of a fork into the chocolate. Leave to set for 1 hr before serving. Will keep for up to three days in an airtight container.