Rhubarb Custard Bars are so sweet and satisfying! Made with a shortbread crust and a tangy custard filling, these bars make the best spring and summer dessert!

Six rhubarb custard bars in two columns with mini spatula under one bar and rhubarb stalks on the side.

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This post was originally posted on 6/14/2020 and updated on 4/17/2024.

Why We Love These Rhubarb Custard Bars

Best spring and summer dessert to use fresh rhubarb.
Easy recipe with a simple shortbread crust and a tangy, creamy custard filling.
No fancy ingredients needed, just simple pantry staples.
These bars have the best texture with a crisp crust and creamy filling.
They are a perfect sweet treat to feed a crowd or bring to a party.

Rhubarb Custard Bars Recipe Ingredients

All Purpose Flour
Salted Butter
Powdered Sugar
Cold Water
Large Eggs
White Sugar
Salt
Diced Rhubarb

Substitution Suggestions

All Purpose Flour: I like to use all purpose flour for shortbread crust because it gives the best texture. White whole wheat flour or whole wheat flour can be used. Note that if you use whole wheat flour, the color of the crust will be darker.
Salted Butter: Unsalted butter can be substituted, but I suggest adding at least a ½ teaspoon of salt to the crust.
Cold Water: no substitute for this. Cold water must be used to help bring the dough together. Do NOT use warm water. It will warm the butter too much and the crust will be gummy.
White Sugar: If you prefer a more tart rhubarb dessert you can use less sugar. Reduce the sugar by a ½-1 cup in the custard filling.
Diced Rhubarb: If you don't have access to fresh rhubarb you can use frozen. Thaw the frozen rhubarb and drain it.

What a perfect recipe to make delicious gooey rhubarb bars. This is going to be your new favorite rhubarb recipe!

How to Make Rhubarb Bars with Shortbread Crust

First, preheat the oven to 350°F and grease a 9x13 baking dish with cooking spray or line with parchment paper leaving at least an inch overhang on the long edges. I prefer a glass dish for these bars, but any will suffice.
In a large mixing bowl, whisk together the 2 cups all purpose flour and 1 cup powdered sugar.
Then cut in the cold cubed butter using a pastry blender or your hands. Once the flour mixture starts to resemble coarse crumbs, stir in the 2 tablespoons of cold water until it forms a dough. The dough should stick together if you squeeze it in your hand.
Next, place the dough in the prepared baking dish and evenly spread it out and pat down using your hands. Bake the crust for 15 minutes.

Butter and dry ingredients cut together in large glass mixing bowl with pastry blender.

Shortbread crust pressed into parchment lined 9x13 baking dish.

While the crust is baking, prepare the rhubarb filling. In a large bowl whisk together the eggs, granulated sugar, flour, and salt until smooth. Stir in the chopped rhubarb.
Once the crust has finished baking, pour the custard filling evenly over the hot crust.
Put back in the oven and bake for 40-45 minutes or until the custard layer is set. The custard is set when it is no longer jiggly in the center.

Rhubarb custard filling in large glass mixing bowl with green spatula.

Cool bars completely before slicing and serving.
Serve at room temperature or chill and then serve. Optional: top with whipped cream or cream cheese frosting.

Top view of rhubarb custard bars in rows with one bar on white round plate.

Storing Rhubarb Custard Dessert

Since this bar is essentially a custard, store the bars in a single layer in an airtight container in the fridge. I actually prefer these bars after they have chilled!

Looking for more rhubarb recipes? Check out these other delicious recipes!

How to Freeze Fresh Rhubarb

Freezing rhubarb is so simple. It is a great way to not waste any fresh rhubarb during the rhubarb season. First wash the rhubarb stalks and pat dry, then trim and dice it up. Place the diced rhubarb in a freezer safe zip top bag. I like to freeze mine in 2 cup portions. Label and date the bag, then place in freezer. I like to lay them flat so they are easier to stack and store in the freezer. Rhubarb can be quite plentiful in the spring and being able to freeze it allows for it to be enjoyed all year long.

Close up side view of three rhubarb custard bars stacked.

Tips for Rhubarb Bars

Gather all your ingredients before you start baking. It is so much easier to bake when all your ingredients are ready. Plus, there is less room for error. Like forgetting an essential ingredient. I'm not saying I've done this, however, I am speaking from experience!
Always read the recipe from start to finish before you start. Again, I am speaking from experience.
Make sure to fluff your flour and powdered sugar a bit before you measure it. When it sits for periods of time it becomes packed. To fluff your flour, just scoop it and dump it a few times or whisk it and then measure it out. If needed, you can sift the powdered sugar too.
If using parchment paper leave an inch overhang on the long edge so you can easily lift the bars out of the dish once completely cooled.
Dice the rhubarb into ½ inch or smaller cubes. It bakes up better than larger pieces.
If using frozen rhubarb or, once they are thawed and drained use kitchen shears to cut them smaller. So much easier than a knife.
The white crust that sometimes forms on the top of the custard bars is the air from the beaten eggs. There's no harm in it. If you don't like it, you can top the bars with whipped cream.
Let the bars cool completely before slicing. The filling needs time to cool and set so the bars stay in tack when sliced.
For clean slices, chill the bars for at least an hour before slicing and clean the knife after each cut.
For even more decadence, top the bars with some creamy whipped topping or cream cheese frosting.

Close up top view of rhubarb custard bar on mini spatula.

Other Delicious Fruit Desserts:

Print Recipe Pin Recipe

3.41 from 152 votes

Rhubarb Custard Bars

Rhubarb Custard Bars are so sweet and satisfying! Made with a shortbread crust and a tangy custard filling, these bars will make the best spring dessert!

Course: Dessert, Snack

Cuisine: American

Prep Time: 20

Cook Time: 45

Servings: bars

Author: Heather

Ingredients

Crust

2 cups unbleached all purpose flour
1 cup powdered sugar
1 cup salted butter, cold and cubed
2 tablespoons cold water

Rhubarb Custard

4 large eggs
2 cups sugar
½ cup unbleached all purpose flour
½ teaspoon salt
4 cups small diced rhubarb

Instructions

Preheat the oven to 350°F and grease a 9x13 baking dish or line with parchment paper leaving an inch overhang on long sides of dish.
In a large mixing bowl, whisk together 2 cups flour and powdered sugar.
Cut in the cold cubed butter with a pastry blender until it resembles coarse crumbs.
Stir in the 2 tablespoons of cold water until a dough forms. It will be crumbly, but will stick together when pressed together.
Pat the dough in an even layer in the prepared baking dish.
Bake the crust for 15 minutes.
While the crust bakes, in a large bowl whisk together the eggs, sugar, flour, and salt until smooth. Stir in the diced rhubarb.
When the crust has finished baking, pour the custard filling over the hot crust.
Bake for 40-45 minutes or until custard has set and is no longer jiggly in the center.
Let the bars cool completely before serving.
Slice and serve with whipped cream or cream cheese frosting.

Nutrition

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Comments

3.41 from 152 votes (144 ratings without comment)