Preheat the oven to 160°C fan/180°C/gas 4. Whisk the butter and sugar together until pale and fluffy, then beat in the marmalade and the eggs, one at a time.

Mix the instant coffee with the boiling water, then whisk it into the mixture. Gently fold in the self-raising flour and baking powder, taking care not to overmix. Spoon the batter into a lined 20cm x 26cm roasting tin.

Transfer the cake to the oven and bake for 25–30 minutes, until firm to the touch and a skewer inserted comes out clean.

While the cake is cooking, make the marmalade coffee syrup. Mix the instant coffee with the boiling water in a small saucepan, add the marmalade and stir over a low heat. Bring to the boil, simmer for 1 minute, then leave to cool.

Once the cake is cooked, leave it in the tin to cool for 5 minutes, then gently lift it out on to a wire rack. Use a skewer to make a few holes in the top, then pour over the syrup.

Serve warm or at room temperature. Any leftovers will keep well in an airtight tin in a cool room for 2–3 days.

FOR DIABETICS: Replace the sugar with 60g xylitol, and use sugar-free marmalade.