Rhubarb Bars are the epitome of spring and early summer! Bright and tangy rhubarb curd with a touch of ginger gets layered on top of a buttery shortbread crust and topped with a silky Swiss meringue. It is sweet, tart, and buttery all in one delicious bar.
If you like lemon bars, you're going to love these rhubarb shortbread bars! Rhubarb curd is just as sweet as lemon curd with an even more mouth-puckering kick. These bars are made with a similar shortbread crust and have a marshmallowy meringue topping to balance out the sweet and sour curd. These rhubarb curd bars have amazing balance in flavors and textures.
Make sure to plan ahead for when you can find that elusive rhubarb - the season runs from April through July. Keep in mind that rhubarb leaves are toxic, so you will only want to use the stems. Most grocery stores or markets will remove all leaves ahead of time, but be sure to remove any additional leftover leaves.
Love rhubarb season and rhubarb desserts? Try these mini strawberry rhubarb galettes, Rhubarb Crumble Cake, or Cherry Rhubarb Pie! Or, if you love shortbread, try more shortbread bar recipes like Salted Caramel Cookie Bars with Shortbread, Pumpkin Pie Crumble Bars, or Apple Crisp Bars.
Why You'll Love This Recipe
Rhubarb. Rhubarb is only available for a short time in the Spring, so I love to make these delicious rhubarb squares to highlight its tart flavor. But you can easily swap frozen rhubarb for fresh rhubarb, so if you are lucky enough to have frozen rhubarb on hand, you can make these any time of year.
Simple bars. Similar to lemon bars, these rhubarb bars are great to make ahead with just 3 easy components!
Tart, creamy, and sweet. These bars have an amazing balance of flavors. Buttery shortbread, tangy curd, and creamy meringue create the perfect balance in every bite.
What Does Rhubarb Taste Like?
Rhubarb is actually a vegetable and looks kind of like celery but with a mix of red and green color. It is very crunchy and fibrous when raw, like celery, and softens to a jam-like consistency when cooked. Rhubarb is very sour and mellows slightly when it cooks, but it does need sugar added to counteract the tartness. It is commonly used to make pies, jams, crisps, crumbles, or poached.
Ingredients
- Rhubarb. Look for fresh, bright red rhubarb. Rhubarb with green stalks will not produce a vibrant color.
- Eggs. Whole eggs are used to combine with the rhubarb to create a tangy rhubarb curd.
- Lemon. This helps to brighten the flavor of the curd for an ultra-sharp taste.
- Granulated Sugar. Used in both the rhubarb curd and the shortbread base.
- Ginger. Freshly grated ginger is added to the rhubarb curd for delightful flavor addition.
For the full ingredient list and quantities, see the recipe card at the bottom of the post.
Substitutions and Variations
- Use frozen rhubarb in place of fresh.
- You can use brown sugar or granulated sugar in the shortbread crust.
- Omit the meringue and dust the top with powdered sugar, similar to lemon bars, for an even easier version.
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How to Make This Recipe
One: Add the rhubarb, sugar, water, and ginger to a saucepan and cook until very soft.
Two: Puree or blend the rhubarb mixture, then pass through a sieve to remove any fibrous pieces.
Three: Whisk the puree together with eggs, flour, lemon juice, and salt, then cook in a saucepan until thickened and coats the back of a spoon.
Four: Pass the mixture through a sieve again, being sure to scrape all curd off the underside of the sieve.
Hot tip! If the color of the curd is too dull from the addition of eggs, add a touch of red or pink food coloring, or use natural food powders to color the curd.
Five: Mix together the butter, four and sugar, then press into a prepared 8x8 inch pan. Par-bake until slightly set.
Six: Add the rhubarb curd to the top of the shortbread crust, then bake until set. Cool completely in the refrigerator.
Seven: Whisk together the sugar and egg white in a Bain Marie until the sugar dissolves, then add the heated egg white mixture to the bowl of a stand mixer (or use a hand mixer).
Eight: Whip on high speed until stiff peaks form. Spread or pipe onto the top of the cooled rhubarb bars then slice and serve.
Expert Tips
- Look for deeply colored rhubarb stems for the best color in your curd.
- Add a touch of red or pink food coloring for a better depth of color. You can also look for natural food coloring powders or hibiscus powder to color your curd.
- Strain the rhubarb after cooking it to remove any very fibrous pieces.
- For clean slices, chill the bars until they are very cold before slicing, and clean the knife between each slice.
- You can pipe the meringue on top of the bars or spread it over the top. Toast the meringue with a blow torch if desired.
Recipe FAQs
Yes, but you should never eat the leaves as they contain dangerous toxins. Only utilize the stalks.
These bars can be flash frozen, then wrapped tightly in plastic wrap and placed into an airtight container. Unwrap and thaw in the fridge, then add any desired toppings before serving.
Rhubarb can be found in many grocery stores and farmers markets from May to June. This produce is incredibly seasonal and typically cannot be found outside of these months. You may be able to find sliced, frozen rhubarb outside of its growing season.
This could be because too much flour was added. A digital scale is recommended to measure your ingredients for the most accurate measurements. The crust also may be hard if it was baked too long.
Storage
Store uncovered in the fridge for one week. The rhubarb bars can also be frozen for up to 3 months.
Once the bars are fully cooled and set (and before adding any powdered sugar or meringue), add the cut bars to a cookie sheet and freeze for about 2 hours. Then, wrap the cut bars in plastic wrap then place in a ziplock bag and freeze for up to 3 months. Unwrap while still frozen, place in the fridge to thaw, then add the powdered sugar or meringue.
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📖Recipe
Rhubarb Bars
Equipment
- Stand mixer with paddle and whisk attachment (or hand mixer)
Ingredients
Rhubarb Puree
- 3 cups fresh rhubarb chopped
- ⅓ cup granulated sugar
- ¼ cup water
- 2 teaspoons ginger freshly grated or minced
Shortbread
- ½ cup unsalted butter room temperature
- ¼ cup granulated sugar
- 1 teaspoon vanilla paste or extract
- ½ teaspoon kosher salt
- 1 cup all-purpose flour
Rhubarb Curd
- ¾ cup granulated sugar
- 3 tablespoons all-purpose flour
- 3 large eggs
- 2 tablespoons lemon juice freshly squeezed
- 1 cup rhubarb puree from cooked rhubarb (above)
- Red/pink food coloring optional
Swiss Meringue (optional)
- 1 egg white from a large egg
- ¼ cup granulated sugar
- pinch kosher salt
- 1 teaspoon vanilla paste or extract
Instructions
Rhubarb Puree
- Clean & chop the rhubarb and add to a pot with the sugar and water. Heat over medium until the rhubarb is completely soft and broken down, about 10 minutes. Add the ginger in the last few minutes of cooking.3 cups fresh rhubarb, ⅓ cup granulated sugar, ¼ cup water, 2 teaspoons ginger
- Transfer the rhubarb to a food processor or blender and puree until smooth. Pass the puree through a fine mesh sieve to get rid of any thick pulp. Scrape off the bottom of the sieve to get all puree. Measure out one cup (~380g) of the puree for the curd and set aside.
- Grease and line an 8x8-inch square pan with parchment slings and preheat the oven to 350℉.
Shortbread
- In a stand mixer fitted with the paddle attachment, cream the butter and sugar for about 3 minutes on medium speed, then add the vanilla, salt and flour.½ cup unsalted butter, ¼ cup granulated sugar, 1 teaspoon vanilla paste or extract, ½ teaspoon kosher salt, 1 cup all-purpose flour
- Press the mixture into the pan as evenly as possible, being sure to get it into the corners and sides (it will be very soft). Bake for 15 minutes, then remove from the oven.
Rhubarb Curd
- While the crust is baking, sift together the sugar and flour, then add the eggs, lemon, and rhubarb puree.¾ cup granulated sugar, 3 tablespoons all-purpose flour, 3 large eggs, 2 tablespoons lemon juice, 1 cup rhubarb puree
- Note: Add red or pink food coloring to brighten up the curd (you can also use freeze-dried strawberry or raspberry powder to do this naturally), as the addition of eggs flattens the color considerably.Red/pink food coloring
- Pour the curd over the partially baked crust, then bake for an additional 20-25 minutes until the curd is completely set in the center (a very slight jiggle is ok, but it shouldn’t be sloshy). Test this by tapping the side of the pan.
- Allow the bars to cool on a wire rack (about 1 hour), then transfer to the fridge for an additional 3 hours to fully chill and set.
Swiss Meringue (optional)
- To make the meringue, fill a saucepan with about 1 inch of water and turn to high heat. Add a heat proof bowl over top that fits securely. You don’t want any of the water touching the bottom of the bowl.
- To the bowl, add the egg white, sugar, and salt and whisk to combine. Continue lightly whisking until the mixture is warm and the sugar granules have dissolved. Check this by rubbing your fingers together in the mixture. It should feel completely smooth - if you can still feel sugar granules, continue cooking. If you have a thermometer, cook it to around 160℉. It should feel rather warm, but not hot.1 egg white, ¼ cup granulated sugar, pinch kosher salt
- One the mixture is ready, add it to the bowl of a stand mixer fitted with the whisk attachment (or use a handheld mixer) and whip on medium speed for about a minute. Turn to high speed and whip until stiff peaks form. Once the meringue hits stiff peaks, add the vanilla, then mix once more to combine. The meringue is ready when the bowl can be turned upside down without any movement or sliding.1 teaspoon vanilla paste or extract
- Pipe on any decoration of your choosing, or spread over the bars, then slice.
- Alternatively, sift powdered sugar over the top of the bars before serving.
Jan W says
Do you have any recommendations if using frozen rhubarb?
Callan Wenner says
Hey there! Just roughly chop the rhubarb and cook it down in a pot - same as the recipe using fresh rhubarb! From there, blend, sieve, and continue with the recipe!
Carol Schroeder says
Thank you for sharing your recipe