Irresistible Rhubarb Custard Bars

If you ask me, rhubarb is one of the most underrated spring ingredients.

These rhubarb custard bars combine a buttery shortbread crust with tangy rhubarb and a smooth, creamy custard layer. The tart rhubarb pieces balance perfectly with the sweet cream cheese topping.

The crust holds everything together without getting soggy, and the custard sets up just right in the oven. It’s a three-layer dessert that looks like you spent hours in the kitchen, but it’s actually pretty straightforward.

These bars are perfect for potlucks or afternoon coffee, and they’re a great way to use up fresh rhubarb when it’s in season.

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What Kind of Rhubarb Should I Use?

Fresh rhubarb is always your best bet for these custard bars, and you’ll find it in season during spring and early summer at most grocery stores and farmers markets. The color of the stalks doesn’t really matter for taste – both red and green rhubarb work equally well, though the red varieties will give your bars a prettier pink hue. Make sure to trim off and discard any leaves since they’re toxic, and only use the stalks for baking. If fresh rhubarb isn’t available, frozen rhubarb is a solid backup option – just thaw it first and drain off any excess liquid before adding it to your recipe so your bars don’t end up soggy.

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Options for Substitutions

Here are some swaps you can make if you’re missing an ingredient or two:

• Rhubarb: This is the star of the show, so I wouldn’t recommend substituting it. However, if your rhubarb is super tart, you can mix in 1 cup of sliced strawberries to balance the flavor.
• Butter: For the crust, you can use cold margarine or even coconut oil if you prefer. Just make sure whatever you use is cold so the crust stays flaky.
• Cream: Heavy cream works best here, but you can use half-and-half if that’s what you have. Your custard will be slightly less rich but still tasty. For the topping, you can also use whipped topping if you’re in a pinch.
• Cream cheese: Full-fat cream cheese is best for the topping, but you can use Neufchâtel (the lighter version) if needed. Just make sure it’s softened to room temperature before mixing.
• Vanilla essence: Vanilla extract works just as well as essence. You can also try almond extract for a different flavor note, but use only 1/4 teaspoon as it’s stronger.

Watch Out for These Mistakes While Baking

The biggest mistake people make with rhubarb custard bars is not cutting the rhubarb into uniform pieces – aim for 1/2-inch chunks so they cook evenly and don’t leave you with some pieces that are mushy while others are still tough.

Another common error is underbaking the custard layer, which leads to a runny filling that won’t set properly – the custard should be just slightly jiggly in the center when you take it out, and it will firm up as it cools completely in the fridge.

Don’t skip chilling the bars for at least 2-3 hours before cutting them, as warm bars will fall apart and make a mess when you try to slice them.

For cleaner cuts, wipe your knife between each slice and consider lining your pan with parchment paper so you can easily lift the whole batch out before cutting into squares.

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What to Serve With Rhubarb Custard Bars?

These bars are pretty rich and sweet on their own, so they pair nicely with a hot cup of coffee or tea for an afternoon treat. I like serving them at potlucks or family gatherings alongside other desserts like brownies or lemon bars so everyone can try a little bit of everything. If you want to make them feel a bit fancier, add a dollop of whipped cream or a scoop of vanilla ice cream on the side. They’re also great for brunch – just set them out on a platter with fresh fruit and some muffins, and you’ve got yourself a spread that’ll make everyone happy.

Storage Instructions

Store: Keep your rhubarb custard bars in an airtight container in the fridge for up to 4 days. They actually taste even better the next day once all the flavors have had time to settle together, so don’t be afraid to make them a day ahead if you’re bringing them to a party or potluck.

Freeze: These bars freeze really well for up to 3 months. Just cut them into individual portions, wrap each one in plastic wrap, and store them in a freezer-safe container. This way you can grab just one or two whenever you’re craving something sweet without thawing the whole batch.

Serve: Let frozen bars thaw in the refrigerator overnight, or at room temperature for about an hour. I prefer eating them cold straight from the fridge since the custard layer is nice and firm, but some people like them at room temperature when the texture is a bit creamier.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 5000-5600
• Protein: 50-60 g
• Fat: 320-350 g
• Carbohydrates: 570-620 g

Ingredients

For the crust:

• 2 1/4 cups flour (I always use King Arthur all-purpose flour for a stable crust)
• 1/4 cup sugar
• 1 cup butter (I like Kerrygold unsalted butter for this)

For the filling:

• 2 cups sugar
• 7 tbsp flour
• 1 cup cream (use heavy whipping cream for a richer custard texture)
• 3 eggs
• 5 cups rhubarb (cut into 1/2-inch pieces for even baking)
• 1/4 teaspoon salt

For the topping:

• 8 oz cream cheese (room temperature, about 70°F, ensures no lumps)
• 3/4 cup sugar
• 1/2 tsp vanilla
• 1 cup cream

Step 1: Prepare the Shortbread Crust

• 2 1/4 cups flour
• 1/4 cup sugar
• 1 cup butter

Preheat your oven to 350°F.

In a medium bowl, whisk together the flour and 1/4 cup sugar.

Cut the cold butter into small cubes and work it into the flour mixture using a pastry cutter, two knives, or your fingertips until the mixture resembles coarse breadcrumbs with some pea-sized pieces of butter remaining.

Press this mixture firmly and evenly into a 9×13-inch baking dish, making sure to create an even layer across the bottom.

Bake for 10 minutes until the crust is set but not yet golden—this par-baking prevents a soggy bottom once the custard is added.

Step 2: Build the Custard Filling

• 2 cups sugar
• 7 tbsp flour
• 1/4 teaspoon salt
• 3 eggs
• 1 cup cream
• 5 cups rhubarb

While the crust bakes, prepare the custard layer.

In a large bowl, whisk together 2 cups sugar, 7 tablespoons flour, and 1/4 teaspoon salt.

In a separate small bowl, whisk the 3 eggs until blended, then add 1 cup heavy cream and stir until combined.

Pour the wet mixture into the dry ingredients and whisk until smooth and well incorporated.

Gently fold in the 5 cups of prepared rhubarb pieces until evenly distributed throughout the custard.

I like to fold gently here to avoid breaking down the rhubarb too much, which keeps the bars from becoming mushy.

Step 3: Bake the Custard Bars

• custard filling from Step 2

Remove the par-baked crust from the oven and immediately pour the custard-rhubarb mixture over it, spreading it evenly.

Return to the oven and bake for 40-45 minutes until the custard is just set but still slightly jiggly in the very center—it will continue to set as it cools.

The edges should be golden and the filling should no longer look wet on top, but overbaking will make the custard tough and grainy.

Step 4: Prepare the Cream Cheese Topping

• 8 oz cream cheese
• 3/4 cup sugar
• 1/2 tsp vanilla
• 1 cup cream

While the bars finish baking, make the topping.

Remove the 8 oz cream cheese from the refrigerator if it hasn’t already reached room temperature (about 70°F)—this ensures it will blend smoothly without lumps.

In a medium bowl, beat the softened cream cheese with 3/4 cup sugar and 1/2 teaspoon vanilla until light and fluffy, about 2-3 minutes.

In a separate bowl, whip the remaining 1 cup heavy cream to stiff peaks.

Gently fold the whipped cream into the cream cheese mixture in two additions, being careful not to deflate the whipped cream too much.

Step 5: Assemble and Chill

• cream cheese topping from Step 4

Remove the custard bars from the oven and let them cool to room temperature, about 30 minutes.

This cooling step is important—if you spread the topping on hot bars, it will melt and become too soft.

Once cooled, spread or dollop the cream cheese whipped cream topping evenly over the bars.

Refrigerate for at least 2 hours before serving to allow the topping to set and the flavors to meld.

I find these bars taste best served chilled, and they hold their shape much better this way.

Irresistible Rhubarb Custard Bars

Delicious Irresistible Rhubarb Custard Bars recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 50 minutes mins

Total Time 1 hour hr 17 minutes mins

Servings 24 pieces

Calories 5300 kcal

Ingredients

  

For the crust::

• 2 1/4 cups flour (I always use King Arthur all-purpose flour for a stable crust)
• 1/4 cup sugar
• 1 cup butter (I like Kerrygold unsalted butter for this)

For the filling::

• 2 cups sugar
• 7 tbsp flour
• 1 cup cream (use heavy whipping cream for a richer custard texture)
• 3 eggs
• 5 cups rhubarb (cut into 1/2-inch pieces for even baking)
• 1/4 teaspoon salt

For the topping::

• 8 oz cream cheese (room temperature, about 70°F, ensures no lumps)
• 3/4 cup sugar
• 1/2 tsp vanilla
• 1 cup cream

Instructions

 

• Preheat your oven to 350°F. In a medium bowl, whisk together the flour and 1/4 cup sugar. Cut the cold butter into small cubes and work it into the flour mixture using a pastry cutter, two knives, or your fingertips until the mixture resembles coarse breadcrumbs with some pea-sized pieces of butter remaining. Press this mixture firmly and evenly into a 9x13-inch baking dish, making sure to create an even layer across the bottom. Bake for 10 minutes until the crust is set but not yet golden—this par-baking prevents a soggy bottom once the custard is added.
• While the crust bakes, prepare the custard layer. In a large bowl, whisk together 2 cups sugar, 7 tablespoons flour, and 1/4 teaspoon salt. In a separate small bowl, whisk the 3 eggs until blended, then add 1 cup heavy cream and stir until combined. Pour the wet mixture into the dry ingredients and whisk until smooth and well incorporated. Gently fold in the 5 cups of prepared rhubarb pieces until evenly distributed throughout the custard. I like to fold gently here to avoid breaking down the rhubarb too much, which keeps the bars from becoming mushy.
• Remove the par-baked crust from the oven and immediately pour the custard-rhubarb mixture over it, spreading it evenly. Return to the oven and bake for 40-45 minutes until the custard is just set but still slightly jiggly in the very center—it will continue to set as it cools. The edges should be golden and the filling should no longer look wet on top, but overbaking will make the custard tough and grainy.
• While the bars finish baking, make the topping. Remove the 8 oz cream cheese from the refrigerator if it hasn't already reached room temperature (about 70°F)—this ensures it will blend smoothly without lumps. In a medium bowl, beat the softened cream cheese with 3/4 cup sugar and 1/2 teaspoon vanilla until light and fluffy, about 2-3 minutes. In a separate bowl, whip the remaining 1 cup heavy cream to stiff peaks. Gently fold the whipped cream into the cream cheese mixture in two additions, being careful not to deflate the whipped cream too much.
• Remove the custard bars from the oven and let them cool to room temperature, about 30 minutes. This cooling step is important—if you spread the topping on hot bars, it will melt and become too soft. Once cooled, spread or dollop the cream cheese whipped cream topping evenly over the bars. Refrigerate for at least 2 hours before serving to allow the topping to set and the flavors to meld. I find these bars taste best served chilled, and they hold their shape much better this way.