Save to Pinterest The kitchen smelled like spring that afternoon, sharp and sweet all at once. I was elbow-deep in flour when my neighbor knocked with a bundle of rhubarb from her garden, stalks so pink they looked almost unreal. I'd never baked with rhubarb before, but something about the way she described her grandmother's crumble made me want to try layering it with custard. The result was messy, a little lopsided, and gone by the next morning.
I made these for a garden party once, and people kept asking if I'd ordered them from a bakery. The layers looked so neat when I cut into them, rhubarb peeking through like stained glass. One friend admitted she'd never liked rhubarb until that day, and another ate three bars standing by the dessert table. I still think about how proud I felt watching them disappear.
Ingredients
- Fresh rhubarb: Choose firm, brightly colored stalks and trim away any leaves, which are toxic. The tartness mellows beautifully when cooked with sugar.
- Granulated sugar (for rhubarb): This sweetens and draws out the juices, creating a jammy texture that holds its shape in the bars.
- Lemon juice: A splash brightens the rhubarb and keeps the flavor from being flat or too earthy.
- Cornstarch (for rhubarb): It thickens the fruit mixture so it doesn't make the base soggy, something I learned after a watery first attempt.
- All-purpose flour: Forms the structure of both the base and crumble topping, giving it that classic shortbread texture.
- Rolled oats: They add a rustic chew and help the crumble stay crumbly rather than dense.
- Unsalted butter: Cold butter is key, it creates those pockets of flakiness when rubbed into the dry ingredients.
- Light brown sugar: The molasses notes make the crumble taste deeper and more caramelized than white sugar alone.
- Salt: Just a pinch balances the sweetness and makes every other flavor stand out.
- Whole milk: Full-fat milk gives the custard richness and prevents it from curdling when heated.
- Egg yolks: These thicken the custard and give it that smooth, velvety finish you want in every bite.
- Granulated sugar (for custard): Sweetens without overpowering the vanilla, letting the custard stay creamy and light.
- Cornstarch (for custard): Helps the custard set without needing to bake it for too long, which can make it grainy.
- Vanilla extract: Use the real stuff if you can, it makes the custard taste warm and rounded instead of artificial.
Instructions
- Get your pan ready:
- Preheat your oven to 180°C and line a 23cm square pan with parchment, letting the edges hang over like little handles. This makes lifting the bars out so much easier later.
- Cook the rhubarb:
- Combine rhubarb, sugar, lemon juice, and cornstarch in a saucepan and cook over medium heat, stirring often, until it softens and thickens into a glossy, jammy mixture. Let it cool while you work on the base.
- Make the crumble:
- Mix flour, oats, brown sugar, and salt in a large bowl, then rub in the cold butter with your fingertips until it looks like chunky sand. You want some pea-sized bits for texture.
- Form the base:
- Press two-thirds of the crumble firmly into the bottom of your pan, making sure it's even and compact. Save the rest for the topping.
- Bake the base:
- Slide it into the oven for 15 minutes until it just starts to turn golden around the edges. Let it cool slightly before adding the next layer.
- Whisk up the custard:
- Heat the milk until it steams, then whisk egg yolks, sugar, and cornstarch in a bowl until smooth. Slowly pour the hot milk in while whisking, then return everything to the pan and stir constantly over medium heat until thick and glossy.
- Layer it all:
- Spread the cooled rhubarb over the baked base, then pour the warm custard on top, smoothing it gently with a spatula. Sprinkle the reserved crumble evenly over everything.
- Bake until golden:
- Return the pan to the oven for 30 minutes, until the crumble is toasted and the custard barely jiggles in the center. Let it cool completely in the pan, then chill for at least 2 hours before slicing.
Save to Pinterest One spring evening, I packed a tin of these bars and met friends by the river. We sat on a blanket as the sun dropped low, and someone said the custard tasted like childhood. I didn't say much, just watched them eat and laugh, crumbs dotting their laps. It's funny how a simple dessert can hold a moment like that, soft and golden and fleeting.
Choosing Your Rhubarb
I used to think all rhubarb was the same until I noticed how much the color varied at the market. The bright pink stalks tend to be sweeter and more tender, while the greener ones can be tougher and more sour. Either works here, but if you're using green rhubarb, you might want to add a little extra sugar to balance the tartness. Look for stalks that feel firm and snap cleanly when bent, and avoid any that are wilted or slimy at the ends.
Storing and Serving
These bars keep beautifully in the fridge for up to three days, covered loosely with plastic wrap or in an airtight container. I like serving them cold, straight from the fridge, because the custard stays firm and the crumble has a nice contrast in texture. If you want to dress them up, a light dusting of powdered sugar or a dollop of whipped cream makes them feel a bit more special. They also freeze well for up to a month, just thaw them slowly in the fridge before slicing.
Making It Your Own
The first time I made these, I threw in a handful of raspberries because I had them sitting in the fridge. The berries bled into the rhubarb and made the whole layer taste brighter and a little more complex. You could also try stirring a pinch of ginger or cardamom into the crumble for warmth, or swap the vanilla in the custard for almond extract if you like that subtle nuttiness.
- Add a few fresh raspberries or strawberries to the rhubarb layer for extra sweetness and color.
- Mix a pinch of cinnamon or ginger into the crumble topping for a hint of spice.
- Drizzle the cooled bars with a simple icing made from powdered sugar and lemon juice for a tangy finish.
Save to Pinterest There's something about the way these bars smell when they come out of the oven, buttery and warm with that hint of tang underneath. I hope they become a favorite in your kitchen, the kind of recipe you reach for when you want something that feels both homemade and a little bit impressive.
Questions & Answers
- → Can I use frozen rhubarb instead of fresh?
Yes, frozen rhubarb works well. Thaw it first and drain excess liquid before cooking to prevent the bars from becoming too watery.
- → How do I know when the custard layer is properly set?
The custard should be just set but still have a slight wobble in the center when you gently shake the pan. It will firm up more as it cools and chills.
- → Can I make these bars ahead of time?
Absolutely. These bars actually taste better after chilling overnight, allowing the flavors to meld. Store covered in the refrigerator for up to 3 days.
- → What can I substitute for rhubarb if it's not in season?
Try using tart berries like raspberries or blackberries, or a mix of strawberries and lemon juice for added tang. Adjust sugar to taste.
- → Why is my crumble topping not golden and crispy?
Ensure your butter is cold when mixing the crumble, and don't pack the topping too tightly. Bake until visibly golden, and allow proper cooling time for the crumble to crisp up.
- → Can I freeze these bars?
Yes, wrap individual bars tightly in plastic wrap and freeze for up to 2 months. Thaw in the refrigerator overnight before serving.