Rhubarb and Custard Crumble Bars (Printable Version)

Layered bars with tangy rhubarb, vanilla custard, and buttery crumble topping—perfect for afternoon tea.

# What You'll Need:

→ Rhubarb Layer

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

→ Shortbread Base and Crumble

05 - 8.8 oz all-purpose flour
06 - 3.5 oz rolled oats
07 - 5.3 oz unsalted butter, cold and cubed
08 - 3.5 oz light brown sugar
09 - 1/2 teaspoon salt

→ Custard Layer

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

# Directions:

01 - Preheat oven to 350°F. Line a 9-inch square baking pan with parchment paper, leaving an overhang on all sides for easy removal.
02 - Combine rhubarb, sugar, lemon juice, and cornstarch in a saucepan. Cook over medium heat, stirring frequently, until rhubarb softens and mixture thickens, approximately 8-10 minutes. Transfer to a bowl and allow to cool.
03 - Combine flour, oats, brown sugar, and salt in a large bowl. Rub in the cold butter using your fingers or a pastry cutter until the mixture resembles coarse breadcrumbs.
04 - Press two-thirds of the crumble mixture firmly and evenly into the bottom of the prepared pan to form a compact base. Reserve the remaining crumble for topping.
05 - Bake the base for 15 minutes until lightly golden. Remove from oven and allow to cool slightly.
06 - Heat milk in a saucepan until steaming but not boiling. In a separate bowl, whisk egg yolks, sugar, and cornstarch until smooth. Gradually pour hot milk into egg mixture while whisking constantly. Return to saucepan and cook over medium heat, stirring continuously, until thickened, approximately 2-3 minutes. Remove from heat and stir in vanilla extract.
07 - Spread cooked rhubarb compote evenly over the baked base. Pour custard layer over the rhubarb in a smooth, even distribution.
08 - Sprinkle reserved crumble mixture evenly and generously over the custard layer.
09 - Bake for 30 minutes, or until crumble is golden brown and custard is just set but still slightly jiggly in the center.
10 - Allow bars to cool completely in the pan at room temperature. Refrigerate for a minimum of 2 hours before carefully lifting out using the parchment overhang and cutting into 16 equal bars.

# Expert Advice:

01 -
  • Three textures in every bite: creamy custard, jammy fruit, and buttery crumble that stays crisp even after chilling.
  • It uses up armfuls of rhubarb without feeling like pie, and tastes fancy enough for guests but easy enough for a quiet Tuesday.
02 -
  • Do not skip chilling the bars. I tried cutting them warm once and ended up with a beautiful mess instead of clean squares.
  • If your custard looks lumpy, whisk it off the heat for a minute. A few vigorous strokes usually smooth it out before it sets.
03 -
  • Taste your rhubarb before cooking. If it is very tart, add an extra tablespoon of sugar to the fruit layer so the bars do not pucker.
  • Let the custard cool for a minute before pouring it over the rhubarb. If it is too hot, it can cause the fruit layer to bleed into the custard and muddy the colors.
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