Tangy Swirled Rhubarb Bars

Spring is when my family starts asking about rhubarb. Those tart pink stalks show up at the farmers market, and suddenly everyone wants something sweet and tangy. But I don’t always want to make a pie from scratch. Sometimes I need something simpler that still feels special.

That’s where these swirled rhubarb bars come in. They’ve got a buttery shortbread crust that you just press into the pan—no rolling pin needed. The filling comes together while the crust bakes, so you’re not standing around waiting. I love how the blood orange plays up the rhubarb’s natural tartness without fighting it.

Want something you can slice up and share? These are perfect. More interested in keeping them all to yourself? I won’t judge. Either way, you’ll end up with a pan of bars that actually tastes like spring.

What Kind of Rhubarb Should I Use?

For these swirled bars, you can use either red or green rhubarb – both will taste great, though the red variety will give you a prettier pink swirl throughout your bars. Look for stalks that are firm and crisp, avoiding any that feel rubbery or have brown spots. Thinner stalks tend to be more tender than thick ones, but either will work just fine as long as you chop them into similar-sized pieces. If you’re buying rhubarb early in the season, it might be a bit more tart, so you may want to taste your rhubarb mixture and adjust the sugar if needed.

Options for Substitutions

This recipe is pretty forgiving when it comes to swaps, so here are some options if you need them:

• Blood oranges: Regular oranges work perfectly fine here. You’ll get the same citrus flavor, just without the deep red color. Meyer lemons are another great option if you want a slightly different taste.
• Rhubarb: Rhubarb is really the star here, so I’d recommend sticking with it if possible. But if you’re in a bind, you could try a mix of tart berries like cranberries or sour cherries, though the texture will be different.
• Vanilla bean: A vanilla bean gives the best flavor, but you can use 1 to 1 1/2 teaspoons of vanilla extract instead. Just add it with the wet ingredients rather than scraping it in.
• Salted butter: Unsalted butter works too – just add a pinch of salt to the dough and filling to balance the sweetness.
• Powdered sugar: In the crust, you can use granulated sugar instead, though the texture might be slightly less tender. Stick with powdered sugar if you can.

Watch Out for These Mistakes While Baking

The biggest mistake you can make with these bars is not browning the butter long enough – you want it to reach a deep amber color with a nutty aroma, which takes a full 5 minutes of careful watching and stirring to prevent burning.

When pressing the crust into the pan, make sure it’s evenly distributed and firmly packed, especially in the corners, or you’ll end up with thin spots that overbake while thicker areas stay underdone.

Don’t skip the chilling step for the crust, as this prevents it from puffing up during baking and creates a sturdy base that won’t get soggy from the filling.

Finally, when swirling the rhubarb jam into the custard layer, use a gentle hand with just a few strokes – over-swirling will muddy the colors and you’ll lose those pretty marbled patterns that make these bars look so good.

What to Serve With Rhubarb Bars?

These rhubarb bars are perfect for an afternoon snack with a hot cup of coffee or tea, especially since the tartness of the rhubarb pairs really nicely with something warm to sip on. I love serving them at spring brunches alongside fresh fruit like strawberries or raspberries, which complement the rhubarb’s tangy flavor. A dollop of whipped cream or a scoop of vanilla ice cream on the side turns these bars into a proper dessert if you’re looking to make them a bit more special. They’re also great packed up for picnics or potlucks since they travel well and can be eaten with your hands.

Storage Instructions

Store: These rhubarb bars keep really well in the fridge. Just cover them tightly with plastic wrap or store in an airtight container for up to 5 days. The flavors actually get even better after a day or two as everything settles together.

Freeze: You can freeze these bars for up to 3 months if you want to make them ahead. Cut them into individual portions, wrap each one in plastic wrap, then place them all in a freezer-safe container or bag. This way you can grab just one or two whenever you need them.

Serve: Let frozen bars thaw in the fridge overnight or at room temperature for about an hour before serving. They’re delicious cold straight from the fridge, or you can let them sit out for 10-15 minutes to take the chill off if you prefer.

Estimated Nutrition

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

• Calories: 3500-3800
• Protein: 35-40 g
• Fat: 175-195 g
• Carbohydrates: 470-500 g

Ingredients

For the rhubarb jam:

• 1 1/4 cups sugar
• 2 blood oranges (zested and juiced for tartness)
• 1/2 vanilla bean
• 5 stalks rhubarb (trimmed and cut into 1/2-inch pieces)
• Pinch of salt

For the crust:

• 7/8 cup salted butter (I prefer Kerrygold for a shortbread-like flavor)
• 1/2 cup powdered sugar
• 1 1/2 cups flour (I always use King Arthur all-purpose flour)

For the filling:

• 3 eggs (room temperature, about 70°F)
• 1 1/4 cups sugar
• 2 blood oranges
• 3/4 cup plus 2 tbsp flour
• 1/2 vanilla bean
• 3/8 cup salted butter (browned and cooled to room temperature)

Step 1: Prepare the Rhubarb Jam

• 1 1/4 cups sugar
• 2 blood oranges
• 1/2 vanilla bean
• 5 stalks rhubarb

Begin by zesting both blood oranges and juicing them into a pot.

Add 1 1/4 cups sugar, the zest, and split vanilla bean to the pot, bringing to a boil over medium-high heat.

Let this simmer for 4-6 minutes to infuse the vanilla flavor and dissolve the sugar completely.

Add the trimmed rhubarb pieces and continue cooking for 7-10 minutes, stirring occasionally, until the rhubarb breaks down and the mixture thickens into a jam-like consistency.

Transfer to a bowl to cool while you prepare the crust—I like using blood oranges for their subtle tartness, which really complements the rhubarb without being too sharp.

Step 2: Brown the Butter and Create the Shortbread Crust Base

• 7/8 cup salted butter

While the jam cools, melt 7/8 cup salted butter in a saucepan over medium heat, stirring occasionally.

Continue cooking for about 5 minutes until the milk solids turn golden brown and the butter smells nutty—watch carefully to avoid burning.

Pour the browned butter into a bowl and freeze for 35 minutes until it solidifies into chunks.

This brown butter gives the shortbread crust a rich, toasted flavor that pairs beautifully with the tart rhubarb filling.

Step 3: Assemble and Chill the Shortbread Crust

• 1/2 cup powdered sugar
• 1 1/2 cups flour
• Pinch of salt
• frozen browned butter from Step 2

While the butter freezes, combine 1/2 cup powdered sugar and 1 1/2 cups flour in a bowl with a pinch of salt.

Once the brown butter is solidified, break it into small chunks and mix into the flour mixture using a fork or your fingertips until the texture resembles coarse breadcrumbs—don’t overwork it or the crust will be tough.

Press this dough firmly and evenly into a parchment-lined 9×13 inch baking dish, going slightly up the sides.

Cover and chill for 30 minutes to prevent the crust from shrinking during baking.

Step 4: Prebake the Crust and Prepare the Custard

• 3 eggs
• 1 1/4 cups sugar
• 2 blood oranges
• 3/4 cup plus 2 tbsp flour

Preheat your oven to 375°F.

After the crust has chilled, bake it for 15-18 minutes until it’s light golden around the edges but still pale in the center.

While the crust bakes, start preparing the custard layer by whisking together 3 room-temperature eggs, 1 1/4 cups sugar, the zest from both blood oranges, and 3/4 cup plus 2 tablespoons flour in a bowl until well combined and pale yellow.

Remove the crust from the oven and let it cool for a few minutes while you brown the second batch of butter.

Step 5: Brown the Second Batch of Butter and Temper the Custard

• 3/8 cup salted butter
• 1/2 vanilla bean

In a separate saucepan, melt 3/8 cup salted butter over medium heat with the remaining 1/2 vanilla bean, cooking for about 5 minutes until deeply browned and fragrant.

Remove from heat and let cool to room temperature—this is crucial so the hot butter doesn’t scramble the eggs.

Once cooled, slowly pour the browned butter into the egg mixture from Step 4, stirring constantly to create a smooth custard.

Remove and discard the vanilla bean piece.

Step 6: Assemble and Bake the Bars

• custard mixture from Step 5
• rhubarb jam from Step 1

Pour half of the custard mixture over the cooled prebaked crust, then dollop most of the cooled rhubarb jam across the surface in spoonfuls—you want swirls, not a solid layer.

Pour the remaining custard over the jam, then top with the remaining rhubarb jam and use a thin knife or skewer to swirl through the layers, creating marble-like patterns.

I find that less swirling actually looks more elegant than overdoing it.

Bake for 25-35 minutes until the custard is just set but still has a slight jiggle in the center—these bars continue to cook as they cool and will firm up beautifully.

Cool completely before cutting into squares and serving at room temperature.

Tangy Swirled Rhubarb Bars

Delicious Tangy Swirled Rhubarb Bars recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 1 hour hr 15 minutes mins

Cook Time 2 hours hrs 25 minutes mins

Total Time 3 hours hrs 40 minutes mins

Servings: 16 bars

Calories: 3650

Ingredients Method

Ingredients

  

For the rhubarb jam::

• 1 1/4 cups sugar
• 2 blood oranges (zested and juiced for tartness)
• 1/2 vanilla bean
• 5 stalks rhubarb (trimmed and cut into 1/2-inch pieces)
• Pinch of salt

For the crust::

• 7/8 cup salted butter (I prefer Kerrygold for a shortbread-like flavor)
• 1/2 cup powdered sugar
• 1 1/2 cups flour (I always use King Arthur all-purpose flour)

For the filling::

• 3 eggs (room temperature, about 70°F)
• 1 1/4 cups sugar
• 2 blood oranges
• 3/4 cup plus 2 tbsp flour
• 1/2 vanilla bean
• 3/8 cup salted butter (browned and cooled to room temperature)

Method

 

1. Begin by zesting both blood oranges and juicing them into a pot. Add 1 1/4 cups sugar, the zest, and split vanilla bean to the pot, bringing to a boil over medium-high heat. Let this simmer for 4-6 minutes to infuse the vanilla flavor and dissolve the sugar completely. Add the trimmed rhubarb pieces and continue cooking for 7-10 minutes, stirring occasionally, until the rhubarb breaks down and the mixture thickens into a jam-like consistency. Transfer to a bowl to cool while you prepare the crust—I like using blood oranges for their subtle tartness, which really complements the rhubarb without being too sharp.
2. While the jam cools, melt 7/8 cup salted butter in a saucepan over medium heat, stirring occasionally. Continue cooking for about 5 minutes until the milk solids turn golden brown and the butter smells nutty—watch carefully to avoid burning. Pour the browned butter into a bowl and freeze for 35 minutes until it solidifies into chunks. This brown butter gives the shortbread crust a rich, toasted flavor that pairs beautifully with the tart rhubarb filling.
3. While the butter freezes, combine 1/2 cup powdered sugar and 1 1/2 cups flour in a bowl with a pinch of salt. Once the brown butter is solidified, break it into small chunks and mix into the flour mixture using a fork or your fingertips until the texture resembles coarse breadcrumbs—don't overwork it or the crust will be tough. Press this dough firmly and evenly into a parchment-lined 9x13 inch baking dish, going slightly up the sides. Cover and chill for 30 minutes to prevent the crust from shrinking during baking.
4. Preheat your oven to 375°F. After the crust has chilled, bake it for 15-18 minutes until it's light golden around the edges but still pale in the center. While the crust bakes, start preparing the custard layer by whisking together 3 room-temperature eggs, 1 1/4 cups sugar, the zest from both blood oranges, and 3/4 cup plus 2 tablespoons flour in a bowl until well combined and pale yellow. Remove the crust from the oven and let it cool for a few minutes while you brown the second batch of butter.
5. In a separate saucepan, melt 3/8 cup salted butter over medium heat with the remaining 1/2 vanilla bean, cooking for about 5 minutes until deeply browned and fragrant. Remove from heat and let cool to room temperature—this is crucial so the hot butter doesn't scramble the eggs. Once cooled, slowly pour the browned butter into the egg mixture from Step 4, stirring constantly to create a smooth custard. Remove and discard the vanilla bean piece.
6. Pour half of the custard mixture over the cooled prebaked crust, then dollop most of the cooled rhubarb jam across the surface in spoonfuls—you want swirls, not a solid layer. Pour the remaining custard over the jam, then top with the remaining rhubarb jam and use a thin knife or skewer to swirl through the layers, creating marble-like patterns. I find that less swirling actually looks more elegant than overdoing it. Bake for 25-35 minutes until the custard is just set but still has a slight jiggle in the center—these bars continue to cook as they cool and will firm up beautifully. Cool completely before cutting into squares and serving at room temperature.