Rhubarb Bars with Buttery Shortbread Crust
These irresistible Rhubarb Bars feature a golden buttery shortbread crust topped with a tangy-sweet rhubarb custard filling that bakes up perfectly every time.
The Only Rhubarb Bar Recipe You Will Ever Need
If you have ever stood in the garden (or the produce aisle) staring at a bunch of fire-red rhubarb stalks and thought, now what? this recipe is your answer. These Rhubarb Bars are the kind of dessert that converts skeptics. One bite of that tangy, jammy filling over a crisp, buttery shortbread crust and suddenly everyone wants the recipe.
Rhubarb has a short and glorious season, and this is one of the very best ways to use it. Unlike a pie, these bars are easy to transport, simple to slice, and just as good cold from the fridge the next morning with a cup of coffee. They land somewhere between a lemon bar and a fruit crumble in the best possible way.
The right pan and quality ingredients make a noticeable difference with bar cookies. A light-colored metal baking pan promotes even browning on the crust without over-cooking the edges, and parchment paper is truly non-negotiable for lifting the bars out cleanly.
Tools & Ingredients We Recommend
Why This Recipe Works
A lot of rhubarb bar recipes end up with a soggy bottom or a filling that weeps liquid all over the plate. This version avoids both problems with a few deliberate choices:
- Pre-baking the crust for 15 minutes sets it up so it stays crisp under the wet filling.
- Flour in the filling acts as a thickener so the custard layer sets firmly instead of staying loose.
- Patting rhubarb dry (especially if using frozen) removes excess moisture before it ever hits the pan.
The optional tablespoon or two of strawberry jam is a trick borrowed from classic strawberry-rhubarb pie. It deepens the sweetness and adds a gorgeous blush color to the filling without overpowering the rhubarb's natural tartness.
Chef's Tip: For the brightest flavor and color, use the reddest rhubarb stalks you can find. The greener the stalk, the more tart and dull the final color will be.
Fresh vs. Frozen Rhubarb
Fresh rhubarb is ideal when it is in season, typically from late spring through early summer. Outside of that window, frozen rhubarb is a completely acceptable substitute. The key is to thaw it fully and squeeze or pat out as much liquid as possible. Skipping this step is the number one reason a filling does not set properly.
Either way, chop the rhubarb into small, uniform pieces, about half an inch. This ensures it softens evenly during baking and every bar gets a good distribution of fruit.
Tips for the Perfect Shortbread Crust
The crust here is intentionally simple: flour, powdered sugar, and cold butter. Cold butter is the secret. It creates a slightly flaky, crumbly texture rather than a dense or greasy base.
- Work quickly with your fingertips or a pastry cutter so the butter does not melt.
- Press the crust firmly and evenly into the pan so it holds together cleanly when sliced.
- Do not skip the pre-bake. Those 15 minutes make all the difference.
Ready to bake? Here is the full recipe from start to finish:
Rhubarb Bars with Buttery Shortbread Crust
These irresistible Rhubarb Bars feature a golden buttery shortbread crust topped with a tangy-sweet rhubarb custard filling that bakes up perfectly every time.
Ingredients
- 1 1/2 cups all-purpose flour, divided
- 1/4 cup powdered sugar, for the crust
- 1/2 cup unsalted butter, cold, cut into cubes
- 2 large eggs, room temperature
- 1 1/4 cups granulated sugar
- 1/4 tsp salt
- 3 cups fresh rhubarb, trimmed and chopped into 0.5-inch pieces
- 1 tsp vanilla extract, pure
- 2 tbsp strawberry jam, optional, for extra sweetness and color
Instruction
Preheat your oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan and line it with parchment paper, leaving an overhang on two sides for easy lifting.
Make the shortbread crust: In a large bowl, whisk together 1 cup of the flour and the powdered sugar. Add the cold butter cubes and use your fingertips or a pastry cutter to work the butter into the flour until the mixture resembles coarse, pea-sized crumbs.
Press the crust mixture firmly and evenly into the bottom of the prepared pan. Bake for 15 minutes, until just lightly golden at the edges. Remove from the oven and set aside.
While the crust bakes, make the rhubarb filling: In a large bowl, whisk together the eggs, granulated sugar, remaining 0.5 cup of flour, salt, and vanilla extract until smooth.
Fold the chopped rhubarb (and strawberry jam, if using) into the egg mixture until evenly coated.
Pour the rhubarb filling evenly over the warm pre-baked crust and spread gently with a spatula.
Return the pan to the oven and bake for 30 to 35 minutes, until the filling is set in the center and lightly golden on top. A toothpick inserted in the center should come out mostly clean with no wet batter.
Allow the bars to cool completely in the pan on a wire rack, at least 1 hour. Lift out using the parchment overhang, dust with powdered sugar if desired, and slice into 16 bars.
Equipment
- 9x13-inch baking pan
- Parchment paper
- Large mixing bowl
- Pastry cutter or fork
- Whisk
- Spatula
- Wire cooling rack
- Sharp knife or bench scraper
Notes
Serving and Storing Your Rhubarb Bars
Once the bars are fully cooled, dust them generously with powdered sugar for a bakery-worthy finish. Slice into 16 squares for a crowd or 12 larger bars if you want a more generous portion.
These bars are wonderful at room temperature but genuinely better cold, straight from the fridge. The filling firms up, the crust stays crisp, and the flavors deepen overnight. If you are making them for a gathering, bake them the day before and let the refrigerator do the work.
Leftovers keep in an airtight container in the fridge for up to 5 days, and they freeze beautifully for up to 2 months. A batch of these in the freezer is a very good thing to have on hand.
