Sweet Potato & Marshmallow Cake

A few days ago I shared my review of Grow Your Own Cake, published by Frances Lincoln. Click through to read more and to enter my giveaway to win your own copy of the book.

This intriguing cookbook features 46 recipes for savoury and sweet cakes and bakes featuring vegetables and fruits you can grow yourself. The author Holly Farrell, an experienced gardening writer, shares invaluable tips on how to grow and harvest each crop, before putting it to use in the recipe provided. Photography is by Jason Ingram, who illustrates both gardening tips and recipes throughout the book.

growyourowncake grown your own cake sweet potato
Book jacket; sweet potato image by Jason Ingram

Pete and I have thus far made two recipes from the book, an Upside-down Pear Cake and this Sweet Potato and Marshmallow Cake, published below with permission from Frances Lincoln. I love the idea of taking a combination associated with American Thanksgiving menus and turning it into a cake.

We weren’t sure what to expect from this cake – in taste, in texture, in appearance. To our surprise the crumb is actually fairly light and not overly sweet, in fact it’s a lovely gently flavoured sponge which would work very well on it’s own, without the ganache filling or marshmallow fluff topping. We over-baked by just a few minutes, which gave the outside a slightly darker colour, but it didn’t affect the taste at all.

I am not sure adding mini marshmallows into the batter serves much purpose – as the cake cooks they seem to melt away leaving odd pockets in the sponge, lined with a crunchy sugar glaze – so I might skip those next time. The sweet potato cake is the real winner in this recipe, and you could lose the marshmallow elements if you wanted to and serve it as a simple unadorned sponge.

Sweet Potato and Marshmallow Cake on Kavey Eats (2)

Sweet Potato & Marshmallow Cake

If sweet potato & marshmallow casserole, the traditional Thanksgiving dish, is too sweet for your turkey dinner, use this great pairing in cake form instead. It is perfect after a long winter’s walk.


For the mashed sweet potatoes:

  • 800-900 g sweet potatoes

For the cake:

  • 400 g plain flour
  • 1 1/2 tbsp baking powder
  • 3/4 tsp salt
  • 1/4 tsp black pepper
  • 1/2 nutmeg finely grated (or 1/2 tsp ground nutmeg)
  • 165 g unsalted butter
  • 250 g light muscovado sugar
  • 4 eggs
  • 450 g mashed sweet potatoes
  • 90 g mini marshmallows

For the ganache:

  • 45 ml double cream
  • 100 g white chocolate

For the decoration:

  • 100 g marshmallow fluff (about half a jar)
  • 100 g marshmallows


  • 2 deep, round 20cm cake tins , greased and base-lined


  • For the mashed sweet potatoes, preheat the oven to 180°C/350°F/gas mark 4. Roast the sweet potatoes for around 45 minutes until they are soft. Remove from the oven and leave to cool completely, then pop them out of their skins. Mash well (use a potato ricer if you have one).

  • For the cake, preheat the oven to 170°C/325°F/gas mark 3.

  • Combine the flour, baking powder, salt, pepper and nutmeg in a bowl and mix well; leave to one side. Beat the butter and sugar together until light and fluffy. Add the eggs, one at a time, beating well to incorporate after each egg. Mix in the mashed sweet potato, then the flour and spice mix

  • Quickly stir in the mini-marshmallows and divide the cake mixture between the two tins. Make sure that all the marshmallows on the surface are coated with mixture to prevent them burning.

  • Bake for 50–60 minutes. To check if it is ready insert a skewer into the cake; if it comes out clean the cake is cooked. 

  • Remove from the oven and leave for 10 minutes in the tins, then turn out on to a wire rack to cool completely.

  • For the ganache, heat the cream in a small saucepan over a medium heat until just under boiling point. Pour over the chocolate and stir until it has melted and is smooth. Leave to cool until the mixture is thick enough to spread without running.

  • To assemble, sandwich the two cake layers together with the ganache, spread marshmallow fluff on the top and sprinkle with whole marshmallows.

Sweet Potato and Marshmallow Cake on Kavey Eats (1)

If you decide to buy this book after reading our content, please consider clicking through our affiliate link, located within the post and in the footnote at the end.

Kavey Eats received a review copy of Grow Your Own Cake from Frances Lincoln, part of Quarto Publishing Group UK. Grow Your Own Cake by Holly Farrell, photographs by Jason Ingram is currently available from Amazon for £14.88 (RRP £16.99).

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40 Comments to "Sweet Potato & Marshmallow Cake"

  1. kaveyeats

    Yeah I thought the idea odd too but its taste and texture are far less odd than I expected!!

  2. kaveyeats

    Ha ha Bintu, you’re welcome and I’ve even provided a photo so you’re a step ahead of where I was!! 😉

  3. Munchies and Munchkins

    I love this idea. I make sweet potato pancakes so I can imagine the flavour of this. I make sweet potato casserole ( thanksgiving style) last year for the first time and I love the marshmallow in it. This book sounds like an interesting one!


    Thanks Rebecca, yeah some classic ideas and some really unusual ones like this! You’re sweet potato pancakes sound excellent!

  4. Catherine

    Sweet potato and marshmallow care sound intriguing and one my nephews would love to help making. Sweet potato and marshmallow casserole on the other hand ???!!!***???!!!


    Yes I’ve encountered the casserole, it’s not for me, it’s far too sweet and sugary to have as part of a roast dinner!

  5. kaveyeats

    It’s a great title isn’t it?! And we’ve enjoyed the two recipes we’ve tested so far.

  6. kate @ veggie desserts

    I love sweet potato in desserts (of course!), and it’s interesting to see it with marshmallows. My uncle used to feed us marshmallow topped sweet potatoes with dinner (he’s American) and it was so wrong alongside vegetables. Definitely more of a dessert thing!


    Yes I’ve always wondered how it’s considered a savoury combination in the USA!!!

  7. Simon @ Zest and Herbs

    I was expecting to see grated raw sweet potato going into the mix more like a trad carrot cake. I will certainly have to give this a try, but definitely without the marshmallow fluff. I once lived with a girl who would spread it on toast but I’ve never understood the appeal myself.


    No I can’t say I’m really a convert to the fluff, is just gloopy sugar suspended in goo!

  8. Laura@howtocookgoodfood

    I love the idea of sweet potatoes in baking cakes, they are a natural cake ingredient with all their sweetness it makes sense to use the in a cake recipe. I think the wonderful looking sponge doesn’t need that marshmallow topping myself!

  9. Mamta Gupta

    Looks good. Was it no too sweet, with that many ‘sweet’ potatoes, as well as sugar. With less sugar, it might be suitable for me and my slightly sweet tooth ;). So many things to try and so little time!


    Actually no, not too sweet and you don’t need to add filling or topping.

  10. Sarah Maison Cupcake

    Loving the look of this cake – the marshmallow combo with sweet potato is especially apt considering Americans put them together for Thanksgiving. Been a while since I baked sweet potato in a cake but it was very tasty and I must do again.


    This was my first sweet potato cake experience and I’m definitely going to try more!

  11. Debi at Life Currents

    I bet this is delicious! And I love the idea of growing the sweet potato for this. I’ve grown potatoes of all kinds before and they’re quite easy to grow. In fact, I’ve stuck them in the ground and totally forgotten about them and they still grow! This is a great recipe!


    Most years we find at least one or two plants come up from a tuber we must have accidentally failed to harvest previously, so as well as the varieties we buy that year, we’ll usually have one or two others, just a plant or two!

  12. kaveyeats

    Yes, I love the idea of growing one’s own ingredients for the recipes!

  13. kaveyeats

    Yes the idea of growing ingredients and then providing a recipe works very well!


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