Rhubarb and coconut custard cake


Yesterday I was faced with a dilemma: I’d bought a few stalks of rhubarb to bake a cake for Mothers’ day, but in the usual shopping frenzy I’d ended up forgetting to buy butter, which didn’t occur to me as a problem until I got together my rhubarb pie ingredients in the evening. I didn’t fancy another trip to the shop so I had to check my recipe collection for a suitable alternative. And although this Rhubarb honey coconut tart ticked all the boxes ingredients-wise, I just didn’t quite fancy a honey flavour right then. (It’s definitely going to be tried out soon, though)

I ended up adapting this intriguing Rhubarb custard tea cake  by Thanh of eatlittlebird, because the thought of hiding a layer of custard in the cake to go along with the rhubarb was just irresistible. I’m really happy that her recipes are so easy to follow since the foodstuffs she gets in Switzerland aren’t much different than ours here in Germany, so I don’t end up having to find creative substitutes all the time. But as with this cake, I usually end up giving it my own twist, and in this case it’s by upping the rhubarb factor and adding coconut flavours.

By upping the rhubarb factor I don’t just mean adding more fresh rhubarb – I had a tub of rhubarb and strawberry “Rote Grütze” (a fruity compote that comes in seasonal flavours and is usually eaten smothered in vanilla sauce) some of which I mixed into the custard while spreading the remainder over the cake for the last 10 minutes of baking, thus adding a moist finish.

If you want to try this version but can’t buy the Grütze, I added the instructions for making a very similar compote to the recipe.


Rhubarb and coconut custard cake

For the compote:

  • 300 gr peeled and diced rhubarb
  • 500 gr strawberries, diced
  • 2 tbsp cornstarch
  • 2 tbsp granulated fine sugar
  • 1 tsp vanilla flavour

For the custard:

  • 40 gr (1/3 cup) bourbon vanilla custard powder
  • 55 gr (1/4 cup) granulated fine sugar
  • 250 ml (1 cup) skimmed milk
  • 2 heaped tbsp rhubarb & strawberry compote
  • 1 tsp vanilla flavour
  • 1 tbsp coconut oil

For the cake:

  • 200 gr (6 1/2 oz) coconut oil
  • 110 gr (1/2 cup) granulated fine sugar
  • 2 large eggs
  • 185 gr (1 1/4 cup) all-purpose flour
  • 2 tsp baking powder
  • 40 g (1/3 cup) custard powder
  • 1 tsp vanilla flavour
  • 2-3 tbsp milk
  • 4-5 stalks of rhubarb, peeled and roughly diced
  • 4 tbsp sugar for sprinkling
  • 4-5 heaped tbsp rhubarb and strawberry compote

For the glaze:

  • 50 gr (2 oz) cream cheese, softened
  • 50 gr (1/4 cup) powdered sugar
  • 2 tbsp cream of coconut, softened
  • 1 tsp vanilla flavour
  • 1 tbsp coconut oil
  • To finish: 1 tbsp shredded coconut


1. To make the Compote: Heat the diced strawberries and peeled and diced rhubarb in a pot. Bring to boil, then reduce the heat and let it simmer gently for 5 minutes until the rhubarb starts breaking down. Put half of the pot into a blender and puree it thoroughly. Take a few spoonfuls of the remaining liquid in the pot and mix it with the cornstarch in a small bowl. Whisk this into the fruit puree, then return the puree together with the sugar and the vanilla to the fruit in the pot and stir well until it thickens. Fill into jars as needed. Cool in the fridge.

2. To make the custard: Heat all but 4 tbsp of the milk in a pot, then stir in sugar and vanilla. Mix the custard powder with the remaining 4 tbsp of milk, then add this to the hot milk. Stirring constantly, bring to a boil then reduce the heat to low and continue stirring until the custard thickens. Take the pot off the stove, stir in the coconut oil first, then the compote. Set aside to cool.

3. Preheat the oven at 180°C (340F). Line the bottom of a 18cm round springform cake tin with baking paper, and grease the sides of the tin.

4. To make the cake: Mix the coconut oil and the sugar in a bowl until fluffy, then add the eggs one at a time, then the vanilla. Mix the baking powder, custard powder and the flour together and then add to the wet ingredients to make a very thick dough. Add the milk to soften it a little, so that it becomes spreadable. It is a very thick dough, though, so beware of it becoming too soft.

5. Assembling the cake: spread 1/3 of the dough over the bottom of the tin. As the dough is so thick, it might be difficult to do so best to put down dollops of dough, then spread them outwards to connect, taking care to cover all of the bottom. Over this, spread the custard, then the remaining dough, repeating the technique of the first part. Finally, add the rhubarb to the top, distributing it evenly over the dough and sprinkling it with 4 tbsp of sugar.

6. Set the cake on the middle rack of the oven and bake for 1 hour and 20 minutes. After that, spread the compote over the top and return to the oven for another 10-15 minutes or until the top thickens slightly. Then remove the cake from the oven and let cool thoroughly (in the fridge after it has reached room temperature).

7. Make the glaze by combining all ingredients and stirring thoroughly. When the cake is cool, sprinkle the glaze over the top in a criss-cross pattern then add some shredded coconut. Transfer the cake onto a cake plate and serve.

Notes: the glaze isn’t absolutely necessary but I thought it would make a nice contrast and complement the rhubarb. It’s from a recipe by Tournadough Alli that I’ve also yet to try once I can get decent local produce.


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