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!
They combine tart spring rhubarb with a creamy vanilla custard filling and buttery crumble topping for a dessert that feels both nostalgic and modern. They have all the flavor of a classic rhubarb custard tart, but in an easier-to-make bar format that slices beautifully after chilling.
Try some of my other bar recipes: Tahini Brownies and Pistachio Lemon Bars.
Rhubarb Custard Bars: Recipe at a Glance
Prep Time
10 mins
Cook Time
55 mins
Total Time
1hr 5mins
Servings
9 Servings
Calories*
410 kcal
Difficulty
Easy
Main Ingredients
Fresh rhubarb, sugar, all-purpose flour, heavy cream, eggs, cornstarch, lemon, vanilla extract, baking soda and butter.
Technique
Preparing a crust in a food processor, whisking the custard base, par-baking the crust, layering the rhubarb and custard and baking the bars.
*Calories are estimated
Table of Contents
Why This Recipe Works
- Easy to make: The shortbread-like crust comes together quickly in a food processor and doubles as the crumb topping.
- Unlike many rhubarb custard bar recipes that become watery after baking, this version uses cornstarch and heavy cream for a custard that slices cleanly and holds its shape beautifully.
- Tested and Reliable: Groceries are expensive! All my Dessert Recipes are tested by me, my team and/or recipe testers before posting.
Ingredients
What I love about this spring dessert recipe is how it comes together with a handful of standard and easy-to-find ingredients, most of which you probably have right now. The fresh tart rhubarb is key. Here is what you will need:
- 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. Also, try my Pistachio Lemon Bars; they have a similar crust.
- Lemon Zest: Adds a fresh citrus note to the crumble. It’s not entirely necessary, but I think it adds a nice layer of flavor. I’m a big fan of citrus flavor. If you enjoy citrus, try my Limoncello Tiramisu and Lemon Pistachio Pound Cake.
- 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.
Refer to the recipe card at the bottom of this post for a full list of ingredients and quantities.
How to Make this Rhubarb Custard Bars Recipe
Step 1. Make the Shortbread Crust. Preheat the oven to 350°F / 175°C. Line an 8-inch or 9-inch square baking pan with parchment paper or aluminum foil. 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.
Step 2. Transfer. Transfer two-thirds of the coarse crumbs to the prepared pan. Save the remaining third and set it aside for now.
Step 3. 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.
Step 4. 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.
Step 5. 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.
Step 6. 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.
Step 7. 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.
Expert Tips
- Use fresh, firm rhubarb when possible. Avoid limp stalks, as they can release too much moisture. Remember that rhubarb leaves are poisonous, so if you are harvesting stalks from your own garden as I do, remove and discard the green leaves and use only the bright red stalks.
- 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.
- 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.
- Watch the jiggle. The center should barely wobble, but the edges should look set.
- If using frozen rhubarb, bake from frozen and expect the bars to need a little extra time. I also encourage you to let the frozen rhubarb thaw in a sieve to remove as much extra liquid from the rhubarb as possible.
- Line the pan with parchment so you can lift the bars out cleanly before cutting.
- For cleaner slices, use a sharp knife and wipe it between cuts. You can also warm the knife under hot water for cleaner cuts. It’s the same technique I would recommend when cutting any other creamy dessert like my Lemon Curd Tart with Pistachios.
Rhubarb Custard Bars Recipe FAQs
Yes. These bars are actually better made ahead because they need several hours in the fridge to set.
Store them in an airtight container in the refrigerator for up to 3 days.
Yes, but the custard texture may soften slightly after thawing. Freeze sliced bars in a single layer, then transfer to a freezer-safe container. Thaw overnight in the refrigerator.
Yes. Rhubarb is naturally tart, but you can reduce the sugar slightly if you prefer a sharper rhubarb flavor.
Yes, absolutely. But I do recommend thawing out the rhubarb in a sieve or colander to remove any excess water.
No, just use a sharp knife to slice the rhubarb and you should be all set.
The bars likely needed more baking or more chill time. The center should still jiggle slightly when removed from the oven, but the edges should be set. Refrigerating the bars for several hours helps the custard fully firm up before slicing.
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Rhubarb Custard Bars Recipe
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 teaspoon Kosher salt
- ¼ teaspoon Baking soda
- 10 tablespoon 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 tablespoon Cornstarch – 16 grams
- 2 tablespoon Lemon juice
- 1 teaspoon 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
- 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.
- 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
Nutrition information is automatically calculated, so should only be used as an approximation.
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