Easy Rhubarb Crumble Cake Recipe {Traybake} + Video

Name: Easy Rhubarb Crumble Cake Recipe {Traybake}
Prep time: 10 min
Cook time: 50 min
Total time: 60 min
Ingredients: 150 g Plain flour (All Purpose) ((1 cup +1.5 tbsp)); 1 Baking powder; 160 g Light brown soft sugar ((3/4 cup - packed)); 1 tsp Ground cinnamon; 1/3 tsp Salt; 100 g Butter ((7 tbsp)); 400 g Rhubarb (trimmed weight - diced into small chunks (3 cups)); 50 g Granulated sugar ((1/4 cup) for drawing moisture from chopped rhubarb only); 250 g Plain flour (All Purpose) ((1+3/4 cups + 1.5 tbsp)); 3 tsp Baking powder; 2/3 tsp Salt; 275 g Light brown soft sugar ((1 cup - packed)); 128 g Butter ((1/2 cup + 1.5 tbsp)); 1 tsp Vanilla; 2 large Eggs; 180 g Buttermilk ((3/4 cup) See notes for substitution)

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This fresh rhubarb crumble cake recipe is a deliciously tender traybake with a crunchy crumb topping that's perfect for sharing at coffee time.

Note, this recipe has been carefully measured in cups and grams for my UK and US friends.

a slice of rhubarb streusel cake being eaten with a gold fork on a plate in front of a cooling rack full of rhubarb traybake squares

I love when it's rhubarb season! As my parents are rhubarb lovers, they always have an abundance of it in the Summer for me to take some home and bake with.

We often mix our raw rhubarb into one of our many fruit crumble recipes for a traditional British dessert. You just can't beat the scrummy butter, flour, and sugar-crumb topping.

As for this year, I decided to turn our rhubarb sticks into a moist rhubarb cake that's easy for sharing. It was inspired by the German crumble cake (Streuselkuchen), that's great for picnics, parties, or a comforting dessert with custard.

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✔️ Why You'll Love This Recipe
🛒 Ingredient Notes
📋 Instructions
👩‍🍳 Substitutions
⚖️ Variations
🔪 Equipment
❄️ Storage
💡Pro Tips
🍽️ Serving Suggestions
❓ FAQ
➕ More Fruit Crumble Recipes
📖 Recipe
💬 Comments

✔️ Why You'll Love This Recipe

Here are a few reasons why we think you'll love this rhubarb coffee cake:

No need for an electric mixer
It's a great way to use up older fruit
A delicious cake made with cheap ingredients
No rubbing is required for the streusel topping
Foolproof & easy buttermilk rhubarb cake to make
A great crowd please that you can eat with your hands
Makes a change compared to normal fresh fruit crumbles

🛒 Ingredient Notes

Please see the printable recipe card with exact ingredient quantities and preparation instructions at the bottom of this post.

labelled ingredients for rhubarb crumble cake

Rhubarb - you can usually find regular rhubarb for sale at a farmers market from April to June. It's also really easy to grow on allotments or in your own backyard as it comes back each year. Or you can defrost and use a whole 500g/1lb bag (give or take) of frozen rhubarb

Granulated sugar - this is white coarse sugar to toss rhubarb in it and draw the excess moisture for a less soggy cake for 20 minutes before stirring into the cake mixture

Plain/all purpose flour - with no leavening agents or a gluten free plain flour of your choice

Baking powder - creates air bubbles to let the cake rise. Note, you may prefer to add ½ teaspoon of baking soda if your rhubarb is more on the green side to remove any slight tart rhubarb taste. It also helps create a slight tender crumb if preferred

Large eggs - these are large free-range eggs

Unsalted butter - this is softened butter at room temperature for the main cake layer, but cold butter can be used as this recipe uses melted butter for the top crumb layer

Soft light brown sugar - for a golden brown colour, or use caster sugar (baking sugar) if more accessible

Vanilla extract - for extra flavour, or you can swap for almond extract

Buttermilk - to create a gentle tangy light and soft cake texture, or you could use the same weight in sour cream. If you can't find it in your local store, mix 1 cup of milk with 1 tablespoon of lemon juice or white vinegar and leave it to rest for a few minutes

Ground cinnamon - to add some warm spice to the large crumbs

Salt - to balance the sweetness and tangy rhubarb, or remove the salt from the list of ingredients if using salted butter

(Optional) Ready-made vanilla icing sugar - I use Betty Crocker and microwave for 30 seconds until runny for easy drizzling

📋 Instructions

First, preheat the oven to 160°c fan/180°c conventional/gas 4/350 F and grease a 13 x 9" baking dish with cooking spray or butter. Then line with baking parchment.

person mixing granulated sugar with diced fresh rhubarb to leave sitting in a bowl to allow the moisture to seep out

1. In a medium bowl, toss the chunks of rhubarb in the granulated sugar and leave to rest for 20-30 minutes.

This will draw any excess moisture out and prevent a soggy cake.

person mixing rhubarb crumble topping into small pebbles with flour, butter, baking powder, cinnamon and brown sugar

2. Now in a small bowl, mix together the crumble topping's dry ingredients, except the sugar.

Then stir in the melted butter with a fork.

Now stir in the brown sugar crumbs until you have larger coarse crumbs that resemble small pebbles and set aside.

person creaming butter and sugar in a stainless steel mixing bowl

3. To make the cake, start by creaming the butter and sugar in a large bowl.

Keep mixing until it is pale and fluffy.

Stand mixers: do this on a medium-high speed

person mixing eggs into butter and sugar to make a sponge cake

4. Now mix in the large eggs and vanilla extract.

I recommend scraping the sides of the bowl to ensure it is fully combined.

person stirring buttermilk and flour into butter and sugar to form a cake batter

5. Stir in a small amount of the buttermilk and flour.

Then gently stir until it has been fully incorporated into the mix.

Repeat until all of the remaining cake mixture and wet ingredients are mixed in.

If mixing in the bowl of a stand mixer: do this on a low speed to avoid overmixing.

person folding in drained diced rhubarb into cake batter

6. Now drain the juices from the resting rhubarb.

Then gently fold them into the batter.

Again, avoid overmixing.

person spreading rhubarb cake batter into a greased and lined Wilton 13 x 9" cake pan the size of a traybake

7. Transfer the cake batter to your prepared pan.

Then smooth with a spatula, making sure you press into the corners.

person spreading an even layer of cookie crumble on top a rhubarb cake before baking in the middle of the oven for 50 minutes

8. Sprinkle the crumble mixture on top of the cake, making sure it is covered.

Then bake for 50 minutes, or until golden. To see if it is ready: insert a skewer in the centre. If it doesn't come out clean, continue to bake for another 10 minutes.

Then let the cake cool for 30 minutes before transferring it to a wire rack and leave to fully cool before icing and slicing.

Simple Icing Drizzle: to ice, I just microwave ready made icing for 30 seconds to make it runny. Then drizzle over the top with a spoon and leave to firm before slicing

vanilla icing drizzled over rhubarb crumb cake and sliced for serving on white baking paper

👩‍🍳 Substitutions

Depending on your dietary needs, here are a few simple swaps you can make:

Rhubarb: swap for diced apples for a classic apple crumble cake, or other fruits such as pear, chopped banana, strawberries, cherries, etc. If using softer fruit, try tossing in cornstarch first to avoid a soggy cake
Butter: swap for plant based butter if required, or coconut oil
Sugar: try swapping for a sweetener version of caster and brown sugar. To remove juices from your rhubarb, you can microwave them first
Buttermilk - you can make it yourself by stirring 1 tablespoon of lemon juice to 1 cup of milk. Just stir and leave it to rest for a few minutes before measuring out what you need
Flour: if wanting a gluten free rhubarb crumb coffee cake, swap for your chosen GF plain o rall purpose flour. Or, if use almond flour for lower carb and wanting more fibre and protein
Eggs: swap for flax eggs for a vegan rhubarb crumble cake, alongside plant-based butter and vegan sugar

close up of pink rhubarb baked in a crumb traybake on cooling rack

⚖️ Variations

Here are a few different ways you can enhance and truly personalise this recipe:

Strawberry rhubarb crumb cake - swap half of the rhubarb for chopped strawberries
Extra spiced - add more warming spices to your sweet crumbles, such as nutmeg, ginger, ground cloves and crushed cardamom pod seeds
Nutty - for extra crunch, add chopped pecans, almond flakes, or seeds etc which toast beautifully
Zesty - stir in some orange or lemon zest for extra flavour

person cutting rhubarb coffee crumble cake with a gold fork on white plate

🔪 Equipment

Please note that as an Amazon Associate, I earn from qualifying purchases made through affiliate links.

*Or a digital kitchen scale and spoons if only working in grams (metric)

close up of cooked rhubarb in a traybake dessert, sliced into squares

❄️ Storage

Storing - we prefer eating rhubarb bars once they have fully cooled, but they can be stored in an airtight container and refrigerated for up to 3 days. If icing, I recommend adding a layer of plastic wrap in between

Freezing - cool to room temperature and again, store in a freezer-safe container for up to 3 months.

Reheating - If you want to eat the next day, defrost in the fridge if required and you can eat cold, or hot after microwaving for 30 seconds

💡Pro Tips

If you can't find buttermilk, make your own by mixing 1 cup of milk with 1 tablespoon of lemon juice or white vinegar and leaving it to rest for a few minutes
Avoid adding large pieces of rhubarb and ensure they are diced evenly so that all the chunks cook at the same time every piece is evenly cooked while baking
Try to harvest the pinkest or redist rhubarb stalks you can as green rhubarb tends to be sour
If preferred, you can rub diced cold butter into the crumble mixture, or use a pastry cutter for quickness
If you don't have a baking tray, you can use a springform pan to easily release the cake from the sides. Or you can bake individual crumble cakes in ramekin dishes, or make rhubarb crumble muffins using a muffin tin etc for easy serving
To ensure the cake is cooked through, ensure you insert a skewer, cake tester, or cocktail stick in the centre. If you see a smear of cake better, you'll need to bake it for another 10 minutes.
To prevent your crumble from over-browning in the oven, cover it with tin foil while baking for longer if needed
Let the cake cool in the tin for 30 minutes to ensure it keeps its shape before turning it out onto a cooling rack

🍽️ Serving Suggestions

Here are a few ways you can eat this rhubarb crumb cake:

Yogurt: enjoy with a dollop of Greek yogurt and extra fresh fruit for a delightful breakfast, or easy tea time dessert or snack

Cream: heat up and serve with a dollop of homemade whipped cream or a scoop of vanilla ice cream. Alternatively, we also like to drizzle cold single cream to soak into the crumb

Custard: rhubarb and custard is a classic combination we enjoy, particularly after heating up the cake

Trifle sponge: soak leftover pieces of this rhubarb streusel coffee cake in jelly (or jello) as part of an extra special rhubarb crumble trifle by James Martin - and use up surplus rhubarb from your garden!

❓ FAQ

Is it safe to eat rhubarb?

If this is your first time baking with fresh rhubarb, then you might not know that the leaves are poisonous. When preparing, cut off and discard the leaves and only use the stalk. Also, make sure you wash and trim any brown parts off.

Do I need to cook the rhubarb before baking?

You might think you need to stew the rhubarb first, but you don't. In my recipe, I simply leave it to rest in sugar first to draw out excess moisture to prevent a soggy cake and make them less tart.

Do I need to peel rhubarb first?

Some people peel rhubarb in case the skin is too tough to eat, but I've never had any problems leaving the skin on and baking.

➕ More Fruit Crumble Recipes

Looking for some new ways to bake with rhubarb? Why not add it to one of these fruit crumbles?

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📖 Recipe

Comments

Anu

August 30, 2025 at 7:59 pm

The recipe is great! But the recipe card had me going back and forth between quantities and instructions above! Wish they were all together in the recipe card. The recipe card is missing the crumble instructions too.

- Vikkie Lee
  
  September 01, 2025 at 1:39 pm
  
  Thanks for bringing this to my attention! I've now tweaked the recipe card which featured the ingredients next to each step to avoid this. Hope this helps if you make it again.
  Thanks,
  Vikkie