About this recipe:Sticky, moist and provides a great talking point when people find out it is made from potatoes. It's the perfect partner for morning coffee or afternoon tea, and makes a great family pudding, especially with a scoop of ice cream.
Cook the potatoes in a steamer set over boiling water for 15 to 20 minutes, until tender, then press through a potato ricer or mash well, then set aside to cool.
Pre-heat the oven to 180 C / Fan 160 C / Gas 4, then butter and line a 20cm deep round cake tin.
Beat together the butter, sugar and vanilla extract until light and creamy. Gradually beat in the eggs, then mix in the ground almonds, baking powder, cooled mashed potatoes, orange and lemon zest. Spoon into the cake tin, smoothing over the surface and baking in the oven for 45 to 50 minutes.
While the cake is cooking put the orange juice in a small saucepan and bring to the boil, reducing by half. Cool, then stir in the sugar. When cake is just firm and a skewer inserted into the middle comes out clean.
Remove from the oven and leave in the tin for 15 minutes then turn out onto a wire rack to cool. Spoon or pour the orange juice mixture over the cake and allow to cool completely before slicing.