Equipment
* optional
Ingredients
Shortbread Crust
- 170 g all-purpose flour, room temperature
- 50 g powdered sugar
- 2 g salt
- 140 g unsalted butter, cold, cubed
Rhubarb Curd Filling
- 450 g fresh rhubarb, chopped into 1cm pieces
- 250 g granulated sugar
- 30 g all-purpose flour
- 4 eggs, large
- 15 ml lemon juice
Optional Garnish
- 1 rhubarb stalk
- 50 g granulated sugar
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 217 kcal
- Protein
- 3 g
- Carbohydrates
- 33 g
- Fat
- 8 g
- Fiber
- 1 g
- Sugar
- 22 g
- Sodium
- 69 mg
- Saturated Fat
- 5 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 3 g
- Polyunsaturated Fat
- 1 g
- Cholesterol
- 65 mg
- Potassium
- 123 mg
- Calcium
- 38 mg
- Iron
- 0.5 mg
- Magnesium
- 8 mg
- Phosphorus
- 45 mg
- Zinc
- 0.3 mg
- Vitamin A
- 81 mcg
- Vitamin C
- 3 mg
- Vitamin D
- 0.3 mcg
- Vitamin E
- 0.4 mg
- Vitamin K
- 10 mcg
- Vitamin B6
- 0.0 mg
- Vitamin B12
- 0.1 mcg
- Thiamin
- 0.03 mg
- Riboflavin
- 0.08 mg
- Niacin
- 0.3 mg
- Folate
- 12 mcg
- Water
- 42 g
Sources: USDA FoodData Central
Method
Preheat the oven to 175°C (350°F). Line a 20cm (8-inch) square baking pan with parchment paper, leaving an overhang on two sides for easy removal.
In a food processor, pulse the 170g flour, 50g powdered sugar, and salt. Add the cold cubed butter and pulse until the mixture resembles coarse meal. Press the dough firmly and evenly into the bottom of the prepared pan.
Bake the crust for 15-20 minutes, until the edges are lightly golden. While baking, proceed to the next step to prepare the filling.
Combine chopped rhubarb and 250g granulated sugar in a saucepan over medium heat. Cook, stirring occasionally, until the rhubarb breaks down into a compote (about 10-15 minutes). Transfer to a blender or food processor and puree until smooth. Let cool slightly.
(Optional) To make rhubarb curls: Using a vegetable peeler, shave long strips from a fresh rhubarb stalk. Briefly poach in a simmering syrup of 50g sugar and 50ml water for 30 seconds. Remove, twist around a chopstick or spoon handle, and let dry. Skip this step if purely focused on flavor.
In a mixing bowl, whisk the eggs, 30g flour, and lemon juice until smooth. Slowly whisk in the warm rhubarb puree. Pour this mixture over the hot crust immediately after removing it from the oven.
Bake for 30-35 minutes at 175°C (350°F), or until the filling is set but still slightly jiggly in the very center. It should not be liquid.
Allow the bars to cool completely in the pan at room temperature, then refrigerate for at least 2 hours to firm up before lifting out by the parchment handles and slicing.
Chef's Notes
- Select the reddest rhubarb stalks you can find to achieve a vibrant pink color naturally. If using mostly green stalks, a single drop of red food gel can correct the aesthetics without affecting flavor.
- Do not attempt to slice these bars while warm; the curd needs the cold environment of the fridge to set into a clean-cut texture.
- Wipe your knife with a damp cloth between every single cut to ensure professional, sharp edges on your bars.
- Unlike lemon bars, rhubarb has a high pectin and fiber content, which yields a slightly thicker, more jam-like texture than a pure custard.
Storage
Refrigerator: 3 days — Cover tightly. Crust will soften over time.
Freezer: 1 month — Freeze cut bars on a tray first, then wrap individually. Thaw in fridge.
Reheating: Serve chilled or at room temperature.
Troubleshooting
Base is soggy or mixed with filling
Cause: Filling was poured onto a cold crust or crust wasn't packed tight enough
Fix: Cannot be fixed after baking; serve as a pudding or crumble
Prevention: Always pour filling while the crust is still hot from the initial bake
Filling is brown/dull color
Cause: Green rhubarb stalks were used or browning occurred during baking
Fix: Dust generously with powdered sugar before serving to hide the color
Prevention: Select the reddest stalks possible; cover loosely with foil if top browns too fast
Cultural Context
While 'Lemon Squares' are a quintessentially American bake sale staple appearing in community cookbooks since the mid-20th century, this variation swaps the citrus for rhubarb—often called the 'pie plant' in the US. It highlights the spring harvest season and bridges the gap between a fruit crumble and a formal custard pastry.
