1 Grease the cake tin and frying pan, then line the cake tin with cling film and the bottom of the frying pan with baking paper. Put the jelly in a heatproof bowl and pour over the boiling water. Gently stir until completely dissolved, then pour into the lined cake tin and put in the fridge to set for at least 1-2 hours.

2 Heat the oven to 180°C/160°C fan/ gas 4. Put the butter and sugar in a large mixing bowl and use an electric hand mixer to beat them together until light and creamy. Add the beaten eggs a little at a time, whisking in between additions until fully incorporated. Sift in the flour, then use a metal spoon to fold everything together. Stir in the orange zest and juice.

3 Use a spatula to scrape the batter into the frying pan and smooth it level. Bake on the middle shelf of the oven for 20-25 minutes until risen and golden and a skewer comes out clean when pushed into the centre. Run a knife around the edge of the cake, turn it out onto a wire rack to cool completely, then put on a serving plate.

4 Once the jelly has set, make the topping. Put the dark and milk chocolate in a heatproof bowl and set it over a pan of steaming, not simmering, water (don’t let the bowl touch the water). Leave to melt slowly without stirring. As soon as the chocolate has melted, remove it from the heat and leave to stand for 15-20 minutes until lukewarm.

5 Using the cling film to help you, lift out the jelly and flip it over on top of the cake. Peel off the cling film, then quickly and carefully spread the cooled chocolate over the jelly and cake to cover. Chill the cake in the fridge for 15 minutes straightaway to prevent the jelly melting.

6 After 15 minutes when the chocolate is starting to set, use a palette knife to make lines: quickly dip the long edge of the knife in the chocolate and lift it straight up. Repeat to make several lines, then make another series of lines at 90 degrees to the first. Chill again in the fridge for at least 5 hours or overnight (see Make Ahead).