Did you know that Rhubarb is a very British dessert ingredient. I mean, it's not like they don't have it in other countries, but in the UK, we just love a Rhubarb Crumble like no-where else. So when my Mum asked if I wanted some Rhubarb from her garden, of course I said yes, and of course I had to bake a Rhubarb Crumble Cake!
In the UK Rhubarb is a very classic option for Crumble. Crumble obviously served with custard. Personally I was never keen on a rhubarb crumble when I was younger, I found it a bit to tart for my tastes - I have a very sweet tooth! However, as I've got older I like it more and more.
I have had in the past clients ask for a Rhubarb Cake, and when we had the tearoom we would often Make Rhubarb upside down cake - which was always a great seller! However, I thought with this crop of Rhubarb from my Mum I would try something slightly different.

Rhubarb, Rhubarb, Rhubarb
This year has been dry in the UK, so the Rhubarb isn't plump and juicy. It is however nice and red, which means it's sweet. The cake recipe below has a baking time, that may vary depending on the rhubarb you have. Some will have more moisture content and therefore take a little longer to bake.
I prepared my rhubarb by cutting off the leaves and root end, rinsing thoroughly in cool water and chopping into pieces about 1cm long. However, if you rhubarb is fatter you might want to chop it down the middle as well. You want your pieces to be big enough to know they are there, but small enough to cook through.

Be careful adding the Crumble
When you are baking this cake, you need to add the crumble part way through. This is because crumble needs to sit on the top. If you add it when the cake is completely unbaked it may sink in. Adding the crumble part way however is a risky business and should be done carefully. I personally left my cake in the oven and carefully pulled out the oven shelf. I then scattered the crumble mix over and very carefully smoothed it over.
The reason care is needed is for 2 reasons - firstly, you don't want to be burning yourself. And secondly, as the cake is not yet fully baked there may be a danger of it sinking if you're too heavy handed with it.

Also, lining your tin is very important. You don't want to tip your cake over to remove it from the tin, because all of the crumble will fall off. Therefore, line the tin with the greaseproof paper overhanging the edges. That way you can use the paper to lift the cake from the tin.
Pro-tip - Where to sell Rhubarb Crumble Cake
This cake is great for Tearooms and Cafes, but for a wedding or celebration cake it's a little trickier. Because of the fruit (is rhubarb a fruit?) in the cake I have kept mine in the fridge. I guess it may be ok left out for a few hours, but I don't think it would be a good cake to go under fondant as the decorating time would be too long and the rhubarb may spoil.

You could however make a layer cake out of it, if it was going to be able to be covered in buttercream and refrigerated, just leave the crumble topping off. It would be great combined with a custard buttercream, made by adding custard powder to your regular buttercream.

Rhubarb Crumble Cake Recipe
Equipment
- 8" or 9" Square cake tin or brownie tin 8" or 9" Round cake tin
Ingredients
Cake
- 350-400 gms Rhubarb
- 175 gms Butter or Baking Spread
- 175 gms Caster or Granulated Sugar
- 3 Large Eggs
- 200 gms Plain Flour Or use 200gms Self Raising Flour and no Baking Powder
- 2 tspn Baking Powder
- 1 tspn Ginger Optional
Crumble
- 50 gms Butter
- 140 gms Flour
- 35 gms Sugar
Instructions
Cake
- Preheat your oven to 170c fan, 190c, 350f, GM4
- Prepare a Brownie tin or an 8" or 9" Square tin by greasing the sides and lining the bottom and sides with greaseproof paper. You want the paper to overhang the sides to make it easier to remove the cake from the tin.
- Chop the rhubarb into small pieces of approx 1cm and put to one side
- In a bowl cream together the butter/baking spread and the sugar until light and fluffy
- Add one egg at a time, beating the mixture in between
- Add the flour, baking powder and ginger and mix until just combined
- Add the rhubarb and hand mix until well distributed.
- Pour into your tin and bake for 30 minutes
Crumble
- Whilst the cake is baking make your crumble mix. Using your finger tips rub together all the ingredients until it resembles breadcrumbs. You can also blitz it in a food processor or use a multi purpose dough blender (link at the bottom of the post)
- When the cake has been baking for 30-35 minutes carefully open the oven and sprinkle to crumble mixture over the top. Be sure to leave the cake in the oven but be careful - firstly you don't want to burn yourself and secondly you don't want your cake to collapse. Read the post for more information.
- Carefully smooth the crumble mixture down and close the oven to bake for a further 15 minutes
- The cake is ready when a skewer placed in the middle of the mixture comes out clean, and when the crumble mix is crunchy. Depending on how juicy your rhubarb is it may take a little longer to bake, but don't worry, it'll just make your crumble crunchier.
- Remove from the oven and allow to cool for 10 minutes or so.
- When cool, run a sharp knife around the edge of the cake, and using your greasproof paper carefully lift the cake from the tin.Don't tip your cake over to remove it, or all the crumble will fall off
- Allow to cool on a wire rack before slicing.
Nutrition

Looking for other unusual cake recipes, try:
Fruit and Nut Chocolate Bars
Tottenham Cake
Lemon Crumble Bars
Brookies
Triple Chocolate Brownie Recipe
Egg White Cake
Raspberry and White Chocolate Cake
Biscoff Layer Cake