Sunday 18 May 2014

Lemon Drizzle Mashed Potato Cake

It’s been a gloriously warm and sunny week here in Sheffield – 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
175g unsalted butter, softened
175g caster sugar
4 eggs
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


Unknown said...

oooh, gorgeous!... i've never made mashed potato cake but have always been intrigued... yours really looks so wonderful with the lemon drizzle... perfect for a sunny day!

Minty said...

If you wanna continue on a mashed potato tip, check out Bolo Polana which is a traditional Mozambican dessert. Nice.

Kavey said...

What Dom said -- intriguing and looks so good!

Johanna GGG said...

if you get into the craving for chocolate cake again perhaps you should try one with mashed potato - many years ago I made a chocolate mashed potato cake and loved it (I also have a favourite boston bun recipe with mashed potato) - I have had this one bookmarked for a while so I am glad to hear you loved it - is it really sticky - I have thought of taking it to a family meal some time and imagine the kids would get quite messy with it.

Katie said...

Hi Minty,
I've never heard of a Bolo Polana before but I've looked it up and it sounds like a cashew version of this almondy cake. Bet that tates lovely and creamy.

Hi Johanna, yes I did wonder if it would work as a choc version. I'll have to experiment.
The cake had a sticky glossy top but wasn't too sticky. The cake seemed to lock the syrup in. Do give it a go

Gluten Free Alchemist said...

The texture of this looks perfect Katie. I love a slightly dense crumb and this one looks lovely and moist. The lemon drizzle sounds gorgeous. Mashed potato seems to be quite popular in gluten free cakes, although I have never tried it myself. Now I've seen yours, I must give it a go!

Choclette said...

I had a lovely chocolate cake at a cafe recently that had potato in it. It gave it a really good texture and has been added to my ever expanding list of things to bake.

The Caked Crusader said...

What an interesting recipe; I know there are German cakes/dumplings that use mash potato but have never tried them.
It looks a lovely texture.

Elle said...

This would be perfect with fresh strawberries and blueberries Katie!Love the addition of the lemon syrup. Thanks for the recipe.