Rhubarb & Marshmallow Cake

As the weather in Sweden is trying really hard to become consistent (I mean it rains for 20 min, sun comes out for 20 min then it’s windy then rains again.. just all over the place) the fruits and veggies are trying their best to grow and become ripe too! Which is why when I found the ripest reddest most luscious looking rhubarb I grabbed a bunch! Came home and sat started thinking what to make with it.

I then remember recently seeing a similar styled cake that Nigella Lawson had set as a challenge for Masterchef Australia contestants. They made a Genoise cake with a roasted rhubarb compote (I think) added some Creme pattissiere and covered it with marshmallow fluff. Now for some of you reading this that don’t bake so much, I understand that some things I just wrote sound intense.. (they’re not though) which is why I created a simpler version of that cake, with easier recipes but I’m sure giving the same sort of tastes!

Mine has two layers of buttery sponge (easy peasy recipe), roasted rhubarb (literally nothing more), and a marshmallow fluff – that’s it!

Please Note that this cake is very sweet because of the marshmallow fluff.. however you can easily just put whipped cream in and it would taste amazing! So for those who like having a dessert but don’t want it to be childish’ly sweet then perhaps go with whipped cream instead of the fluff. However for those who love a good sugar rush then this is your go to!!! It’s totally not hard to bake and it looks pretty fancy if you burn off the marshmallow fluff on the outside! 😉

Here’s how you bake it!


For the Butter Cake (this is for three 6″ cake tins, or two 8″ cake tins) –

  • 3 Eggs
  • 300g (1.5 Cups) Sugar
  • 350g (1.5 Cups) Flour
  • 2 tsp Baking powder
  • 1 tsp Vanilla extract (or vanilla sugar)
  • 75g Butter (melted & cooled)
  • 150ml Milk

For the roasted rhubarb –

  • 8 rhubarb stalks (roughly 200g – my rhubarb weren’t super long so just play it by ear)
  • 50-75g sugar

For the marshmallow fluff –

  • 6 egg whites
  • 300g sugar
  • 2 tbsp vanilla extract
  • 1 tbsp corn starch


  1. Start by turning the oven on to 175C (325 F) and line your cake tins – I’ve used two 8” cake tins for this cake.
  2. In a stand mixer or a bowl with a handheld mixer, whip up the eggs and sugar until pale in colour and thick/fluffy in texture.
  3. Then sift in the flour and baking powder and add in the vanilla. Mix until combined.
  4. Then add in the melted butter and milk. And mix until thoroughly combined and your batter is thick and glossy.
  5. Pour into prepared pans and bake for 40 min (time cane vary depending on cake tin size and oven).
  6. Once golden brown on the top and a cake tester comes out clean, take it out and let it cool for 15 min before removing from the tins. Then let them cool completely before filling.

For the roasted rhubarb –

  1. If your oven isn’t on already then turn it on to 200C (350F)
  2. Line a baking tray with foil. Cute your rhubarb to roughly 5cm lengths (I think that’s roughly 2 inches).
  3. Place the cut rhubarb on the tray and sprinkle the sugar over them. Coat the rhubarb with the sugar and then bake in the oven for 15 min until soft but not overly soft that the break apart as soon as you touch them. You want a little bite to them.
  4. Take out from the oven and set aside until cooled.

For the marshmallow fluff –

  1. Pour a little water (roughly quarter way full) in a small saucepan, pit over the stove and set the heat to medium.
  2. In a stand mixer’s bowl (or a bowl if you are using a hand held mixer) add in your egg whites and sugar.
  3. Then place the bowl with egg whites and sugar over the saucepan with warming water and whisk (this is called a baine Marie). Whisk them until the sugar granulated are no more (you can just touch it with your finger tips and see if you feel any sugar granules, if not then your done)
  4. Take the bowl with the egg whites and sugar, while the bottom so there is not steam, and place back onto your stand mixer (or get your hand held mixer ready) and whip on high speed for 5-8 min until you see a thick glossy merengue.
  5. Add in the corn starch and vanilla and then continue whipping until combined.
  6. Place into a piping bag (if you want or you could just spoon it out) the. Set aside for assembly.

Assembly –

  1. Take one of the cakes, and pipe a thin layer of the marshmallow fluff on. Cover with all of the rhubarb. Then pipe another thin layer of the marshmallow fluff.
  2. Place the second layer of cake on top and cover the entire cake with the marshmallow fluff. If you want, you can burn off the edges of the marshmallow for a toastier taste and effect and drizzle some left over rhubarb juice for some taste and colour on top.

And voila! Your ultimate sugary cake is done!!! Enjoy!


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