It’s been a gloriously warm and sunny week here in
– about time too! Earlier in the week I had planned to bake some form of chocolate
cake, but the sunshine made me yearn for something fresh and zingy instead, and
lemon was the obvious choice. I wanted to try something a bit different and
remembered seeing an old episode of River Cottage on TV where one of the chefs
who works with Hugh Fearnley-Whittingstall made a lemon cake with a secret
ingredient – mashed potato!
On first consideration mashed potato may sound like an odd ingredient for a cake, but if I had suggested pumpkin or sweet potato cake I doubt many people would have been overly surprised. The cake is also gluten free and potato flour is a common ingredient in gluten free baking, so on reflection using mashed potato in a cake is not that odd a concept. That being said I was still very eager and excited to try it out myself.
The mashed potato doesn’t replace any of the standard cake ingredients – they are all still there in their equal quantities, it is simply an additional ingredient. I imagined using mashed potato in a cake would result in a very dense and heavy sort of cake – maybe even one a little gummy, but let me re-assure you this cake turned out to be amazingly light and soft. Not heavy or dense in the slightest.
The cake baked evenly and despite its rather compact crumb appearance it was incredibly light, soft and moist. The lemon flavour really shone through, especially as it’s doused in a zingy lemon syrup once removed from the oven. I would describe it as ‘damp’ but in the most delicious way possible, rather than ‘damp and soggy’ which is not good for a cake.
Surprisingly despite using 3 lemons it wasn’t overpoweringly lemony. The potato seemed to mellow out the lemons sharp acidity giving the finished cake a flavour similar to a well made lemon curd. Fresh and lemony, but nicely balanced and sweet too.
It has to be one of the simplest looking, yet most delicious lemon cakes I’ve ever made. The potato gave it a fabulous texture, reminiscent of cakes made with sour cream. It kept just as damp and delicious for the 4 days it lasted. I didn’t have any berries with me at the time but I can imagine it would be great with some fresh raspberries on the side. Worthy of a picnic or BBQ dessert. Do give it a go.
Lemon Drizzle Mashed Potato Cake
(Adapted from River Cottage by Hugh Fearnley-Whittingstall)
175g unsalted butter, softened
175g caster sugar
100g ground almonds
75g white rice flour
2 tsp gluten free baking powder
2 large baking potatoes (around 400g raw = 250g cooked & mashed)
Finely grated zest of 3 lemons
For the topping
Juice of 2 lemons
55g caster sugar
Prepare you mashed potato in advance. Cook it in the skin, then mash it without adding any additional butter or milk and set aside until cold.
Preheat the oven to 180C. Grease and line an 8inch/20cm springform cake tin.
Finely grate the zest of the lemons and set it aside to use later. Mix the ground almonds, rice flour and baking powder together and set aside.
In a large bowl, beat together the butter, sugar and lemon zest until light, pale and fluffy, around 3-5 minutes. Beat in the eggs, one at a time, adding a spoonful of almond flour mix with each addition to stop the mixture curdling.
Once the last egg is added, scatter the rest of the almond flour mix over the top and fold into the mixture.
Weigh out and add 250g of cold mashed potato to the bowl and gently whisk until the potato is incorporated and no large clumps remain. Try not to beat all the air out of the batter.
Spoon the mixture into the cake tin and bake for 30-40 minutes, or until a skewer inserted into the centre comes out with just a few moist crumbs clinging to it. Check it after 30 minutes to make sure it is not browning too much, and quickly cover with a sheet of foil if it is.
Meanwhile, squeeze the juice from the lemons and stir in the caster sugar.
Remove the cake from the oven and immediately prick the top all over with a skewer. Use a spoon to gradually pour the lemon syrup over the top of the cake, letting it soak in before adding more. Make sure to spread it all over the cake evenly.
Leave the cake to cool completely before serving