1

Preheat the oven to 180°C, fan 160°C, gas mark 4. Grease a 20cm square loose-bottomed cake tin with low-fat spread and line with baking paper.

2

Put the black beans, 2 of the eggs and the vanilla extract in the bowl of a food processor and blitz until smooth.

3

In a large bowl, beat together the low-fat spread and brown sugar using a hand-held electric whisk until pale and fluffy. Add the remaining egg, beating well. Add the black bean mixture to the bowl and stir until combined. Finally, fold in the cocoa powder, baking powder and bicarbonate of soda, until well combined.

4

Pour the mixture into the prepared tin and bake for 20 minutes or until a skewer inserted into the centre of the cake comes out clean.

5

Meanwhile, make the meringue topping. In a large, clean, dry bowl, whisk the egg whites using a hand-held electric whisk until soft peaks form. Gradually add the caster sugar, 2 tbsp at a time, until combined, then beat for a final 2 minutes until you have a thick, glossy meringue. Sift over the cocoa and cornflour, then gently fold into the meringue.

6

Remove the cake from the oven and gently spread the chocolate meringue over the top. Return to the oven and bake for a further 35-40 minutes, until the meringue topping is crisp and golden.

7

Let the cake cool in the tin for 30 minutes, then gently remove. Transfer to a cake stand, dust over the extra cocoa powder and serve.