Heat oven to 180C/160C fan/gas 4 and line a loose-based 20cm cake tin with baking parchment. Put the butter and chocolate in a medium saucepan and heat gently, stirring all the time, until melted.

Put 2-3 tbsp of the marmalade in a small bowl and set aside. Off the heat, stir the rest of the marmalade and the sugar into the buttery melted chocolate, and mix well, then break in the eggs and mix again. Finally, stir in the flour in three batches, folding lightly until combined. Scrape into the tin and smooth the top.

Bake for 45-55 mins, rotating the tin halfway through so it bakes evenly. Keep an eye on it in the later stages as (depending on your marmalade) there may be a tendency for the top to scorch. After about 30 mins, cover loosely with foil. If it starts to get a little dark, tent loosely with a sheet of foil.

The cake is cooked when the centre is firm when gently touched, and a skewer inserted in the centre comes out with a very few crumbs attached, like a brownie.

Allow to cool for 10 mins, then turn out and leave to cool right-side-up on a wire rack. Heat the reserved marmalade in the microwave until runny, then brush all over the cake to glaze. Leave to cool before serving.