Rhubarb and Blueberry Crumble Cake



I went to a BBQ at some friends’ the other day, and decided last minute to bring a cake. Since I was leaving on holiday the very next morning I hadn’t done a shop, and as such, I didn’t have many things to inspire a cake. But I did have rhubarb in the freezer, so I decided to make one of my very favourite cakes, a rhubarb crumble cake (my recipe is adapted from this here one from the SORTED Food boys).

Since the frozen rhubarb looked a little lackluster in colour, I decided to throw in some frozen blueberries too; I didn’t have very many left in the freezer though,  and I’m definitely going to try adding more next time.

I’ve never tried making this with frozen rhubarb, only fresh, and I was a bit worried that it would release a lot of water when baking, so I added 1 tbsp of flour to the chopped rhubarb pieces. And since, as predicted, the frozen rhubarb did make the cake a whole lot wetter than fresh rhubarb would have, I also ended up baking the cake for 20 mins longer than I normally do. The wetter than usual rhubarb also sort of absorbed most of the crumble topping! But it was still delicious. I do prefer making this with fresh rhubarb though. I may have to forego the rhubarb all together, out of season, and make this with sour apples and berries instead. Even if rhubarb is the bomb.com.

I always make two of these cakes at once, because it tends to disappear fairly quickly, and keeps really well (even if the crumble topping tends to loose some of its ‘oomph’), and also, I’ve found that a bunch of rhubarb will usually be in the 600 g range, which is what you need for two cakes. It stays moist for days, and is very good for breakfast/an afternoon or late night snack (especially if you heat it up in the microwave for ten seconds!). But if you only want to make one, just half the ingredients below 🙂

Anywho! Here’s what you need:

  • 200 g soft butter
  • 200 g sugar
  • 4 eggs
  •  2 tsp vanilla essence
  • 200 g self-raising flour
  • 600 g frozen rhubarb, chopped into 2 cm pieces more or less (or fresh rhubarb, if you have that on hand!)
  • 1 tbsp flour, for the rhubarb (omit if using fresh rhubarb)
  • 50 g frozen blueberries
  • 3-4 tbsp sugar for the rhubarb (this sort of depends on how sour the rhubarb I have on hand is)

For the crumble topping:
60 g butter, 100 g plain flour, 80 g sugar, preferably unrefined cane sugar (which is what I use for baking most of the time anyways – it’s a little better for you, tastes a little fruitier and some say it’s sweeter, and I’ve never had trouble substituting this for caster sugar in baking; I wouldn’t use it for caramel though, as it melts a bit differently than refined sugar!).

Preheat your oven to 190 degrees Celsius / 375 degrees Fahrenheit / gas mark 5. Line two 20 cm square baking pans with baking parchment, and set aside.

In a large bowl, cream together the softened butter and sugar, beat in the four eggs and vanilla essence, then finally fold in the flour.

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Divide the batter between the two pans, making sure to spread it out into the corners (it will be a fairly thin layer, about 1-1.5 cm, but it will rise when baking).

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Slice the rhubarb, toss with the 3-4 tbsp sugar (and the 1 tbsp of flour, if using frozen rhubarb). Add the frozen blueberries.

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Make the crumble topping by rubbing together the flour and butter until it resembles bread crumbs (no need to be super precise here), then mixing in the sugar.


Scatter the rhubarb/blueberry mixture evenly on the batter, followed by the crumble topping.

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Bake for 30 mins if using fresh rhubarb, and 30-50 mins if using frozen (if the cakes still look very wet at the 30 minute mark, leave them in until they begin to brown, checking every 5 minutes).

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P.s.: keep the cake covered, but make sure what you cover it with doesn’t touch the top of the cake, as this will make the crumble topping disintegrate, which is a shame.

P.p.s.: it also travels well! Here’s me eating some in the car  on the way to France, and a picture of the sun shining though the funny clouds through the roof of the car:

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