Rhubarb Crumble Slice

Prep Time 20 mins

Cook Time 45 mins

Rest Time 2 hrs

Total Time 3 hrs 5 mins

Cooking Method: Baking, Simmering

Cuisine: Modern Australian

Courses: Sweets

Difficulty: Intermediate

Cooking Temp: 180 C

Servings: 1

Best Season: Suitable throughout the year

Description

My foodie friend Don recently gave me a bunch of his home-grown rhubarb. Don is a fantastic gardener and I always appreciate the chance to cook with fresh produce straight from his garden.

Rhubarb is technically a herbaceous perennial vegetable, grown for its thick pink-to-red stalks. Although it’s a vegetable, it’s usually treated like a fruit in desserts because of its bright, tart flavour, which becomes beautifully balanced when cooked with sugar.

Rhubarb isn’t an everyday ingredient for many people, however, when you do get your hands on some fresh stalks it’s a wonderful ingredient for baking and definitely worth trying. Its tangy flavour pairs beautifully with sweet ingredients and buttery pastries.

Only the stalks are edible. The large green leaves contain high levels of oxalic acid and are poisonous, so they should always be discarded.

Preparing rhubarb is simple, just trim the ends, remove the leaves, rinse the stalks and chop them ready for cooking.

With Don’s fresh rhubarb, I decided to make this Rhubarb Crumble Slice, a buttery shortbread base topped with a jammy rhubarb filling and finished with a golden crumble topping.

Quick Summary

This Rhubarb Crumble Slice combines a buttery shortbread base, tangy rhubarb filling and a golden crumble topping. It’s an easy rhubarb dessert recipe that balances sweet and tart flavours beautifully, making it perfect for afternoon tea, sharing with friends, using up fresh rhubarb from the garden or trying something new from the market.

Why You’ll Love This Recipe

Perfect balance of flavours – tangy rhubarb with sweet crumble topping
Simple pantry ingredients most kitchens already have
Great for sharing at afternoon tea or dessert
A delicious way to use fresh rhubarb from the garden or market
Keeps well, making it ideal for preparing ahead

Below you’ll find the full recipe for this easy Rhubarb Crumble Slice, including ingredients, step-by-step instructions, video and helpful tips for getting the best result.

Ingredients

Part 1 The Shortbread Base

150 g plain flour
50 g icing sugar
120 g salted butter, cold and cubed
1 tsp vanilla extract or paste
1/4 tsp salt

Part 2 The Rhubarb Filling

4-5 rhubarb stalks, chopped (about 3 cups)
1/2 cup caster sugar
1 tbsp lemon juice
1 tsp vanilla bean paste
2 x 2 tbsp water
1 tbsp cornflour
1 tsp white miso (Optional but worth it)

Part 3 The Crumble Topping

3/4 cup rolled oats
1/2 cup plain flour
1/2 cup brown sugar
80 g salted butter, melted
1/4 tsp cinnamon
1/4-1/2 cup pecans, chopped. See Tip 1.

Method

Prep the Rhubarb

1
Trim and discard the leaves (toxic). See Tip 2.
2
Rinse stalks well.
3
Peel stems only if very thick or stringy.
4
Chop into 1–2 cm pieces.

Part 1. Make the Shortbread Base

5
Preheat oven to 180°C (fan forced).
6
Lightly butter and line a 20cm square tin with baking paper.
7
Mix 150 g plain flour, 50 g icing sugar and a pinch of sea salt flakes.
8
Add the 1 tsp vanilla to about 1/4 of the cold butter. See Tip 3.
9
Then rub the remaining butter into the flour, icing sugar, salt mix.
10
Add vanilla butter and mix in.
11
Mix until crumbly, like damp sand. See Tip 4.
12
Add dough to the baking tin and press firmly to form the base.
13
Bake 12–15 minutes, until lightly golden.
14
Allow to cool.

Part 2. Cook the Rhubarb Filling

15
Add 3 cups rhubarb, 1/2 cup caster sugar, 1 tbsp lemon juice, 1 tsp vanilla bean paste and 2 tbsp water to a saucepan.
16
Cook on medium to medium-low heat, bringing it to a gentle simmer.
17
Simmer 8–12 minutes, until rhubarb is soft and jammy. See Tip 5.
18
In a small bowl, mix 1 tbsp cornflour with 2 tbsp water until smooth. See Tip 6.
19
Stir the cornflour slurry into the hot rhubarb and cook 1–2 minutes until thick and glossy.
20
Optional miso: loosen 1 tsp miso with a scoop (large spoonful) of hot rhubarb filling, then stir it in. See Tip 7.
21
Remove from heat and cool slightly.

Part 3. Make the Crumble

22
Combine 3/4 cup rolled oats, 1/2 cup plain flour, 1/2 cup brown sugar and a pinch of cinnamon.
23
Stir in 1/4 to 1/2 cup chopped pecans. See Tip 8.
24
Add 80 g melted butter and mix until clumpy.

Assemble and bake

25
Spread rhubarb filling evenly over the base.
26
Scatter crumble on top.
27
Bake 25–30 minutes at 180°C, middle shelf, until golden and bubbling at the edges.
28
Cool completely before slicing. See Tip 9.
29
Slicing option diagrams for 8, 12 or 16 slices
30
Enjoy!
31
Store covered overnight or freeze slices individually.
32
Or for same same but different, you can have... Same easy yummy shortbread base, totally different sweet treat Chocolate Ganache Shortbread Slice

Watch How To Make Rhubarb Crumble Slice

33
Rhubarb is deliciously sweet and tangy. This recipe is easier than you might think.

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Note

Serve warm or cold with sour cream (my personal favourite), cream, ice cream or custard.
Packs perfectly for lunches, yummy deserts, snacks and treats. See Tip 11.

Keywords: rhubarb crumble slice, rhubarb slice, easy rhubarb dessert, rhubarb baking, crumble slice, shortbread base

Tips:

Best nuts to use:
- Pecans: buttery and slightly sweet, my top pick with rhubarb. Pecans + rhubarb = magic!
- Almonds (slivered or chopped): classic, mild, very bake-friendly
- Walnuts: earthier; great if you’re using cinnamon in the crumble
- Hazelnuts: more “gourmet”, extra toasty flavour when baked

Remember that rhubarb leaves must be discarded. Only the stalks are safe to eat.
Adding the vanilla to the butter separately helps avoid sticky dough.
Crumbly dough is correct. If it presses together in the tin, it’s perfect. Do not over-mix and don’t roll into a ball.

It’s ready when some pieces still hold their shape, the mix looks glossy, and it’s not watery. Keep pieces chunkier if you want visible pieces after cooking. Dice smaller if you want it more uniform/jammy.
Always mix cornflour with cold water first before adding it to the hot rhubarb to avoid lumps.
Miso is optional but magic. It adds depth without tasting savoury.
The pecans toast as the slice bakes and add gorgeous buttery crunch.
Don’t rush the cooling. The slice sets as it cools and cuts much more cleanly when completely cooled, or even better, chilled for a couple of hours. It’s worth waiting for. Store covered overnight or freeze slices individually.