There are few things that signal the true arrival of warmer days quite like the sight of bright, rosy stalks of rhubarb at the market. It’s a nostalgic flavor, a perfect bridge between the coolness of spring and the full heat of summer. This recipe captures that beautiful moment in one perfect, portable dessert. It’s a treat built on layers of pure delight: a buttery, tender shortbread crust, a creamy, sweet custard filling, and the tart, jewel-like bite of fresh rhubarb woven throughout.
Think of this as the sophisticated, less-fussy cousin of a rhubarb pie. It’s the perfect thing to bake for a weekend gathering, to bring to a potluck, or simply to have sitting on your counter for a lovely afternoon pick-me-up with a cup of tea. Don’t be intimidated by the layers; the process is straightforward and utterly rewarding. We’ll walk you through every step to ensure a pan of pure sunshine that looks as beautiful as it tastes.
Ingredients
This recipe is all about the beautiful contrast between the simple, rich crust and the vibrant filling. We’ve broken down the ingredients into two parts to keep things organized and easy.
For the Buttery Shortbread Crust:
- 1 cup (125g) all-purpose flour
- ¼ cup (50g) granulated sugar
- ¼ teaspoon salt
- ½ cup (113g or 1 stick) unsalted butter, cold and cut into small cubes
For the Creamy Rhubarb Custard Filling:
- 3 cups fresh rhubarb, washed and sliced into ½-inch pieces (about 3-4 stalks)
- 1 cup (200g) granulated sugar
- ¼ cup (30g) all-purpose flour
- 3 large eggs
- ¼ cup heavy cream or whole milk
- 1 teaspoon pure vanilla extract
- A pinch of salt
Instructions
Follow these steps carefully for bar-baking success! The most important virtue here is patience—allowing the bars to cool completely is the secret to perfect, clean slices.
- Prep Your Pan and Oven: Preheat your oven to 350°F (175°C). Line an 8×8-inch or 9×9-inch square baking pan with parchment paper, leaving a bit of overhang on two sides. This will act as a sling to lift the bars out easily later.
- Make the Shortbread Crust: In a medium bowl, whisk together the flour, sugar, and salt. Add the cold, cubed butter. Using a pastry blender, two knives, or your fingertips, cut the butter into the flour mixture until it resembles coarse, damp sand.
- Press and Par-Bake: Dump the crust mixture into your prepared pan. Press it down firmly and evenly across the bottom to create a solid base. Bake for 15-20 minutes, or until the edges are just beginning to turn a light golden brown.
- Prepare the Filling: While the crust is baking, prepare your custard. In a large bowl, whisk together the sugar, flour, and pinch of salt. This prevents the flour from clumping. Add the eggs, one at a time, whisking well after each addition until the mixture is smooth and pale. Whisk in the heavy cream and vanilla extract.
- Add the Rhubarb: Gently fold the sliced rhubarb pieces into the custard mixture until they are all evenly coated.
- Assemble and Bake Again: Once the crust is par-baked, carefully remove it from the oven. Pour the rhubarb custard filling evenly over the hot crust. Return the pan to the oven and bake for another 40-50 minutes. The bars are done when the custard is set around the edges and the center has just a very slight wobble to it (it will continue to set as it cools).
- Cool Completely (The Most Important Step!): This is the key to perfect bars! Let the pan cool completely on a wire rack to room temperature (this can take about 2 hours). Once at room temp, cover the pan with plastic wrap and transfer it to the refrigerator to chill for at least 4 hours, or preferably overnight. This firm-up time is essential for the custard to set properly for slicing.
- Slice and Serve: Once thoroughly chilled, use the parchment paper overhang to lift the entire block of bars out of the pan and onto a cutting board. Use a large, sharp knife to cut into squares. For extra-clean cuts, wipe the knife clean between each slice. Serve chilled.
Helpful Tips & Delicious Variations
- Rhubarb Prep: If your rhubarb stalks are very thick, you can slice them in half lengthwise before dicing them to ensure they cook through evenly.
- Frozen Rhubarb: You can absolutely use frozen rhubarb! Do not thaw it first; simply toss the frozen pieces with the custard mixture and add 2-3 minutes to the final baking time.
- Strawberry-Rhubarb Twist: For a classic combination, substitute 1 cup of the rhubarb with 1 cup of sliced fresh strawberries.
- Add Some Spice: A teaspoon of ground ginger or the zest of one orange added to the custard filling provides a wonderful, warm complexity that pairs beautifully with the rhubarb.
- Storage: These bars are best stored, tightly covered, in the refrigerator. They will keep beautifully for up to 4 days and, in my opinion, taste even better on day two!
Enjoy every sweet, tangy, and creamy bite