Rhubarb Custard Bars Recipe

Sliced rhubarb custard bars on a wooden board.

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My Rhubarb Custard Bars are sweet, tart, creamy, buttery, and the perfect spring treat. They’re perfect for brunches, spring gatherings, potlucks, or just an afternoon coffee break. This is an incredibly easy recipe to prepare that looks fancy. I think you’re going to love it!

Prep Time10

Cook Time55

Total Time1 5

Course: Dessert, Side Dish

Cuisine: American

Diet: Vegetarian

Servings: Bars

Author: Luay Ghafari

Cost: $20

Equipment

8-inch or 9-inch square baking pan
Food Processor

Ingredients

For the Crust and Topping

1¾ cup All purpose flour - 218 grams
½ cup Granulated sugar - 100 grams
1 tsp Lemon zest
½ tsp Kosher salt
¼ tsp Baking soda
10 tbsp Butter (cold and cut into cubes) - 141 grams

For the Filling

2½ cup Fresh rhubarb (trimmed and sliced into ½-inch pieces) - 300 grams
1 cup Granulated sugar - 200 grams
3 Large eggs - 150 grams
½ cup Heavy cream - 120 grams
2 tbsp Cornstarch - 16 grams
2 tbsp Lemon juice
1 tsp Vanilla extract
Pinch of salt

Instructions

Preheat the oven to 350°F / 175°C. Line an 8-inch or 9-inch square baking pan with parchment paper or aluminum foil.
Make the Shortbread Crust. Add the flour, sugar, lemon zest, salt, baking soda, and cold butter to a food processor. Pulse until the mixture forms a crumbly dough that clumps together when pressed.
Transfer. Transfer two-thirds of the coarse crumbs to the prepared pan. Save the remaining third and set it aside for now.
Press and Par-Bake. Press into the bottom of the prepared pan using your hands, the bottom of a cup or an offset spatula. Bake the crust for 15 minutes in the preheated oven.
Make Custard. While the crust bakes, make the custard. In a large bowl, whisk together the sugar, eggs, heavy cream, cornstarch, lemon juice, vanilla, and salt until smooth.
Add Rhubarb and Custard. Remove the crust from the oven. Scatter the sliced or diced rhubarb evenly over the hot crust. Pour the custard mixture over the rhubarb.
Add Crumble. Crumble the remaining crust mixture over the top. You want even coverage, but it’s okay for the custard rhubarb mixture to peek through.
Bake. Return the pan to the oven and bake for 35-40 minutes, until the edges are set and the center just barely jiggles. Cool completely, then refrigerate for at least 4 hours before slicing. After chilling, the silky custard filling becomes perfectly sliceable while the buttery crumble topping stays tender and crisp. Serve the rhubarb bars cold or at room temperature.

Notes

Refer to the blog post above if you need step-by-step recipe photos.

Key Ingredient Notes:

Fresh Rhubarb Stalks: Fresh rhubarb is best here, but frozen rhubarb can work if used from frozen and baked a little longer. But do try to make this recipe during rhubarb season in late spring/early summer.
Butter: You will need cold butter for a crumbly, shortbread-style crust. Use unsalted butter, but if you only have salted butter, just omit the salt from the recipe.
Flour: All-purpose flour is fine for the crust. If you have pastry flour, you can use that, but all-purpose is totally fine!
Cornstarch: A key ingredient to help thicken and stabilize the custard.
Heavy Cream: This is important. You want to use a heavy or whipping cream for the custard. No shortcuts here. The higher fat percentage is important for a properly set custard.

Tips for Success:

Don’t over-process the crust. Just pulse the food processor until the crust just comes together. Or you can use a bowl and a pastry blender or pastry cutter and mix the dough manually by hand.
Line the pan with parchment so you can lift the bars out cleanly before cutting.
Don’t skip the chill time. This is key. You want the custard to set and cool before slicing. Otherwise, it may end up being way too loose.
For cleaner slices, use a sharp knife and wipe it between cuts. You can also warm the knife under hot water for cleaner cuts.

Nutrition