Rhubarb and Custard Crumble Bars (Printable)

Tangy rhubarb meets creamy vanilla custard under a buttery crumble topping. A delightful British springtime dessert.

# What You Need:

→ Rhubarb Layer

01 - 14 oz fresh rhubarb, trimmed and chopped
02 - 5.3 oz granulated sugar
03 - 1 tablespoon fresh lemon juice
04 - 1 tablespoon cornstarch

→ Shortbread Base and Crumble

05 - 2 cups all-purpose flour
06 - 1 cup rolled oats
07 - 10.6 oz unsalted butter, cold and cubed
08 - 3.5 oz light brown sugar
09 - 1/2 teaspoon salt

→ Custard Layer

10 - 1.25 cups whole milk
11 - 2 large egg yolks
12 - 2.1 oz granulated sugar
13 - 2 tablespoons cornstarch
14 - 1 teaspoon vanilla extract

# How-To Steps:

01 - Preheat oven to 350°F. Line a 9-inch square baking pan with parchment paper, leaving overhang on sides for easy removal.
02 - In a saucepan, combine rhubarb, sugar, lemon juice, and cornstarch. Cook over medium heat, stirring frequently, until rhubarb softens and mixture thickens, approximately 8 to 10 minutes. Transfer to bowl and allow to cool.
03 - In a large mixing bowl, combine flour, oats, brown sugar, and salt. Using your fingertips or a pastry cutter, rub in cold butter until mixture resembles coarse breadcrumbs.
04 - Press two-thirds of crumble mixture firmly into the prepared pan to create an even base layer. Reserve remaining mixture for topping.
05 - Bake base for 15 minutes until lightly golden. Remove from oven and allow to cool slightly.
06 - Heat milk in saucepan until steaming but not boiling. In a separate bowl, whisk together egg yolks, sugar, and cornstarch until smooth. Gradually add hot milk while whisking continuously. Return mixture to saucepan and cook over medium heat, stirring, until thickened, approximately 2 to 3 minutes. Remove from heat and stir in vanilla extract.
07 - Spread cooled rhubarb compote evenly over baked base. Pour prepared custard layer over rhubarb, spreading smoothly.
08 - Sprinkle reserved crumble mixture evenly across custard layer.
09 - Bake for 30 minutes until crumble is golden brown and custard is set.
10 - Cool completely in pan at room temperature, then refrigerate for at least 2 hours. Lift out using parchment overhang and cut into 16 bars.

# Expert Suggestions:

01 -
  • The custard layer adds a creamy surprise that balances the rhubarb's sharp bite perfectly.
  • You get all the comfort of a traditional crumble in a portable, shareable bar form.
  • The buttery crumble on top stays wonderfully crisp even after chilling.
  • It uses up fresh rhubarb beautifully without needing strawberries to sweeten it.
02 -
  • Don't skip chilling the bars before cutting, or the custard will ooze out and the layers won't hold their shape.
  • Make sure your butter is truly cold when making the crumble, or it will turn greasy instead of crumbly.
  • Let the rhubarb filling cool before spreading it on the base, or it can make the crust soggy.
03 -
  • Freeze the butter for 10 minutes before making the crumble if your kitchen is warm, it makes all the difference.
  • Whisk the custard constantly while it thickens to avoid lumps, and take it off the heat as soon as it coats the back of a spoon.
  • Line the pan with parchment on all sides, not just the bottom, so the bars lift out in one clean piece.
Go Back