Preheat your oven to 180C (350F). Grease a muffin tin or line it with silicone muffin molds. In a mixing bowl, beat together the caster sugar and eggs until pale and fluffy.

Sift in the self-raising flour and baking powder, then gently fold them into the egg mixture until just combined. Spoon the batter into the prepared tin, filling each mould about halfway.

Bake for 10-12 minutes, until risen and golden. Cool in the tin for a few minutes, then transfer to a wire rack to cool completely.

While the sponges cool, warm the orange marmalade or jelly gently in a small saucepan over low heat until it becomes spreadable.

Once the sponges are completely cool, use a piping bag or teaspoon to add a small dollop of the warmed marmalade to the centre of each one. Let it cool and firm up.

Melt the dark chocolate in a heatproof bowl set over a saucepan of gently simmering water, stirring until smooth. Dip the top of each cake into the melted chocolate, making sure the jelly is fully covered, then return to the wire rack to set.