Rhubarb and Custard Crumble Bars (Printable)

Tangy rhubarb with creamy custard and buttery crumble topping. A classic British springtime dessert perfect for tea.

# What You'll 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

# Cooking 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 - Combine rhubarb, granulated sugar, lemon juice, and cornstarch in a saucepan. Cook over medium heat, stirring frequently, until rhubarb softens and mixture thickens, approximately 8-10 minutes. Remove from heat and allow to cool.
03 - Mix flour, oats, brown sugar, and salt in a large bowl. Rub in cold butter using your fingertips or pastry cutter until mixture resembles coarse breadcrumbs.
04 - Press two-thirds of crumble mixture firmly into bottom of prepared pan to create an even base. Reserve remaining one-third for topping.
05 - Bake 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, granulated sugar, and cornstarch until smooth. Slowly pour hot milk into egg mixture while whisking constantly. Return combined mixture to saucepan and cook over medium heat, stirring constantly, until thickened, approximately 2-3 minutes. Remove from heat and stir in vanilla extract.
07 - Spread cooled rhubarb compote evenly over baked base. Pour custard layer over rhubarb, spreading to distribute evenly.
08 - Sprinkle reserved crumble mixture evenly over custard layer.
09 - Bake for 30 minutes until crumble is golden and custard is just set.
10 - Allow bars to cool completely in pan, then refrigerate for at least 2 hours before removing from pan and cutting into 16 bars.

# Expert Tips:

01 -
  • The rhubarb cuts through the sweetness with a bright, tangy punch that wakes up your taste buds.
  • Creamy vanilla custard nestled between buttery crumble layers makes every bite feel like a hug.
  • They slice cleanly, travel well, and look impressive without any fuss.
  • You can make them ahead and serve them cold, which is a lifesaver for gatherings.
02 -
  • If you don't chill the bars long enough, they'll be too soft to cut cleanly and the layers will slide apart.
  • Cold butter is crucial for the crumble. If it's too warm, you'll end up with a greasy, dense topping instead of light, crumbly clusters.
  • Stir the custard constantly while it cooks, or it will scorch on the bottom and taste bitter.
03 -
  • Don't skip the chilling time. It's tempting, but warm bars fall apart and the custard won't have that clean, sliceable texture.
  • Reserve a few extra tablespoons of crumble mixture to patch any bare spots on top before baking.
  • If your rhubarb releases a lot of liquid, simmer it a bit longer until it's thick and jammy, or the bars will be soggy.
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