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Rhubarb custard bars pack a nostalgic punch of sweet and tart that always reminds me of springtime gatherings. With a buttery base and creamy custard top scattered with vibrant rhubarb, these bars are surprisingly easy to pull together for a picnic or coffee break treat.
I first made these when an elderly neighbor brought over a basket of rhubarb from her garden. One bite, and I was hooked on this recipe’s balance—the zestiness of the rhubarb just sings against the creamy filling and crunchy base.
Ingredients
- All-purpose flour: Gives the base firmness and helps set the custard
- Cold butter: Creates a flaky tender crust—look for unsalted butter with a clean aroma
- Powdered sugar: For the crust dissolves easily for a melt-in-your-mouth bite
- Granulated sugar: In the filling balances rhubarb’s sharpness
- Salt: Sharpens flavors and rounds out sweetness
- Large eggs: Hold the custard together and give a rich creamy texture
- Fresh rhubarb: Brings bold tartness—choose firm stalks with a glossy sheen and vibrant pink-red color
- Optional powdered sugar: For dusting adds a pretty finish and touch of extra sweetness
Step-by-Step Instructions
- Prepare the Crust:
- In a medium bowl blend all-purpose flour with powdered sugar thoroughly. Cut the cold butter into small cubes and use fingertips or a pastry blender to work it into the flour mixture until it looks like coarse breadcrumbs. Be thorough so no large butter chunks remain. This will ensure a tender base. Press evenly into a well-greased 9-by-13-inch pan making sure you reach all corners for even baking.
- Bake the Crust:
- Slide the pan into a preheated 350 degree oven. Bake for 10 minutes just until the surface is set but not colored. This step allows the crust to firm up before you add the filling so it will not go soggy. Remove from oven and set aside but keep the oven on.
- Mix the Custard:
- In a clean bowl whisk together granulated sugar flour and salt. Crack in the eggs and whisk until the mixture turns slightly pale and smooth with no streaks left. This process incorporates air and gives the custard a soft texture.
- Add the Rhubarb:
- Fold chopped rhubarb into the custard mix making sure the fruit is evenly distributed. Fresh rhubarb gives the best color and texture but if you use frozen dry the pieces first to prevent excess liquid in the bars.
- Fill the Pan:
- Pour the custard and rhubarb mixture evenly over the warm pre-baked crust. Use a spatula to nudge the filling into all corners so each bite will have plenty of fruit and smooth custard.
- Bake to Perfection:
- Return the pan to the oven and bake for 35 to 40 minutes. Check at 35 minutes—the custard should be set but with a slight wobble in the center and the edges should be lightly golden. Avoid overbaking which will make the texture chalky rather than creamy.
- Cool and Finish:
- Let the bars cool completely in the pan which allows the custard to finish setting. Dust with powdered sugar if desired for a pretty finish then slice into bars using a sharp knife wiping between cuts for clean squares. These are easiest to cut once fully cooled or chilled.
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Rhubarb was always an early sign of spring at our house and I love how it transforms in this recipe from a mouth-puckering tart stalk to something soft mellow and so beautiful in color. My kids always ask for seconds especially if I let them help sprinkle the powdered sugar on top.
Storage Tips
Once the bars are completely cool cover the pan tightly with foil or transfer bars to an airtight container. They keep well in the fridge for up to four days and the flavor even improves after a night’s rest. For longer storage wrap bars well and freeze for up to three months. Thaw in the fridge overnight before serving and add a fresh dusting of powdered sugar before enjoying.
Ingredient Substitutions
If you are out of rhubarb diced strawberries or a mix of strawberry and rhubarb works beautifully. For a gluten-free option swap in a good blend of gluten-free flour for the base and filling. If you prefer less sweetness reduce the sugar in the filling slightly or dust with a lighter hand on the topping. Using brown sugar in the filling will add a caramel note if you want a slightly deeper flavor.
Serving Suggestions
Serve bars chilled as is for a refreshing treat or with a dollop of whipped cream. They look lovely on a dessert platter with fresh berries or edible flowers for spring or summer gatherings. For an afternoon snack pair with a cup of hot tea or coffee. They also travel well making them great for picnics or potlucks.
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I have learned to always make a double batch since these bars disappear faster than you expect. That first taste of lush custard and tart rhubarb is a reminder to savor spring’s best gifts while they last.
Frequently Asked Questions
- → Can I use frozen rhubarb for these bars?
Yes, frozen rhubarb works well. Thaw and drain excess liquid before adding to the filling.
- → What can I substitute if I don’t have powdered sugar for the crust?
Regular granulated sugar can be used, though the texture may be slightly different. Powdered sugar creates a more delicate crust.
- → How do I know when the custard is set?
The center should no longer jiggle and the edges will appear lightly golden. Let cool before slicing.
- → Is it necessary to dust with powdered sugar?
Dusting is optional but adds a touch of sweetness and enhances the presentation of the bars.
- → Can I prepare these bars ahead of time?
Absolutely. Store them covered in the refrigerator for up to three days for best freshness.