Rhubarb and Custard Crumble Bars (Printable)

Tangy rhubarb and vanilla custard layered with buttery crumble. A delightful British springtime dessert treat.

# What You Need:

→ Rhubarb Layer

01 - Fresh rhubarb, trimmed and chopped - 14 oz
02 - Granulated sugar - 2.6 oz
03 - Fresh lemon juice - 1 tablespoon
04 - Cornstarch - 1 tablespoon

→ Shortbread Base and Crumble

05 - All-purpose flour - 8.8 oz
06 - Rolled oats - 3.5 oz
07 - Unsalted butter, cold and cubed - 5.3 oz
08 - Light brown sugar - 3.5 oz
09 - Salt - 1/2 teaspoon

→ Custard Layer

10 - Whole milk - 10.1 fl oz
11 - Large egg yolks - 2
12 - Granulated sugar - 2.1 oz
13 - Cornstarch - 2 tablespoons
14 - Vanilla extract - 1 teaspoon

# Directions:

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

# Expert Suggestions:

01 -
  • The three textures, crisp base, silky custard, crunchy topping, make every bite feel purposeful and complete.
  • Rhubarb season is short, and this recipe captures it perfectly without any fuss or fancy equipment.
  • They slice cleanly, travel well, and look bakery-worthy even when you're still in your pajamas.
02 -
  • Don't skip chilling the bars, I tried slicing them warm once and ended up with a custard landslide that tasted great but looked terrible.
  • If your rhubarb is especially tart, add an extra tablespoon of sugar to the fruit layer, it will save you from puckering faces.
  • Make sure your butter is actually cold when you make the crumble, warm butter turns it into a dough instead of a crumbly topping.
03 -
  • Use the parchment overhang to lift the entire slab out of the pan before slicing, it makes cutting so much easier and cleaner.
  • If your custard looks a bit lumpy after cooking, strain it through a fine mesh sieve before pouring it over the rhubarb.
  • Let the rhubarb cool completely before layering, hot fruit under custard can cause curdling or uneven setting.
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