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These rhubarb bars transform the tart spring vegetable into a luxurious dessert that balances sweetness and tang perfectly. The combination of buttery shortbread and juicy rhubarb creates an irresistible treat that disappears quickly whenever I make it.
I first made these bars when my neighbor dropped off a huge bundle of garden rhubarb. After my family devoured the entire pan in one evening, they became our official spring celebration dessert that everyone requests as soon as the first rhubarb appears.
Ingredients
- Butter: Softened to room temperature for that perfect crumbly yet tender texture
- Granulated sugar: Balances the tartness of the rhubarb beautifully
- Vanilla extract: For warmth and depth in the shortbread layers
- All purpose flour: Providing structure without toughness
- Kosher salt: Enhancing all flavors especially the buttery notes
For the rhubarb filling
- Fresh rhubarb: Chopped into bite-sized pieces for the perfect texture
- Grenadine syrup: The secret to achieving that gorgeous ruby color naturally
- Sugar: To tame the natural tartness of rhubarb
- Flour: Helps thicken the filling, preventing a soggy bottom
- Lemon juice and zest: Optional but adds brightness to the filling
For the glaze
- Powdered sugar: Creates that perfect sweet finish
- Milk: Thins the glaze to drizzling consistency
- Vanilla extract: Complements the shortbread flavor
- Salt: Balances the sweetness for a professional finish
Step-by-Step Instructions
- Prep the Rhubarb:
- Chop rhubarb into consistent pieces, splitting each stalk lengthwise first ensures no overly large chunks. Soak in grenadine for at least an hour, stirring occasionally. This infuses beautiful color while the syrup starts breaking down the tough fibers. The longer it soaks, the redder your bars will be.
- Make the Shortbread Base:
- Beat butter until smooth and creamy, taking time to ensure there are no lumps. Add sugar and beat thoroughly for a full two minutes. This incorporation of air creates the perfect tender texture. Mix in vanilla, then gently incorporate flour and salt just until combined. Overmixing at this stage makes tough shortbread.
- Prepare the Pan:
- Line your baking pan with parchment paper for easy removal. Press just over half the dough into the pan, creating a slight rim around the edges to contain the filling. Chill the pressed dough for optimal texture. Cold shortbread going into a hot oven creates that perfect crisp yet tender crust.
- Bake the Base:
- Bake until the edges turn light golden brown. If the center puffs up, gently press it down while still hot. This creates the perfect flat surface for your filling. Let cool slightly before adding filling to prevent sogginess.
- Create the Filling:
- Drain the soaked rhubarb thoroughly. Combine with sugar and flour, which will thicken the juices as it bakes. Add lemon if using. The acid brightens the flavor but can be omitted for pure rhubarb taste. Pour this mixture evenly over the partially cooled crust.
- Add the Crumble Top:
- Break the reserved dough into rustic chunks. Scatter these pieces over the filling, leaving some gaps where the ruby filling can peek through. This creates an attractive finish and allows steam to escape during baking.
- Bake to Perfection:
- Bake until the shortbread topping turns golden and the rhubarb is completely tender when pierced with a fork. This slow bake ensures the filling thickens properly without burning the shortbread. Cool completely before finishing and slicing.
- Glaze and Serve:
- Mix powdered sugar with minimal liquid for a thick drizzleable consistency. Add vanilla and salt to enhance flavor. Drizzle over cooled bars and allow to set before cutting into squares.
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The grenadine is truly the magical ingredient in this recipe. I discovered this trick after years of making pale green rhubarb desserts that tasted wonderful but lacked visual appeal. The syrup not only adds vibrant color but also contributes a subtle fruity undertone that complements rhubarb perfectly.
Seasonal Variations
Rhubarb pairs beautifully with other spring fruits if you want to create variations. Strawberries are the classic companion, adding natural sweetness and complementary color. Simply replace up to half the rhubarb with hulled and quartered strawberries. Raspberries also work wonderfully, lending their own ruby hue and bright flavor profile. For a more complex flavor, try adding a quarter teaspoon of ground cardamom to the shortbread dough.
Make Ahead Tips
These bars actually improve with a rest in the refrigerator, making them perfect for entertaining. You can prepare the entire recipe up to two days before serving, waiting to add the glaze until a few hours before presentation. The flavors meld and the texture sets perfectly with this rest time. If making further ahead, freeze the unglazed bars, then thaw in the refrigerator overnight and add fresh glaze before serving.
Serving Suggestions
While delicious on their own, these rhubarb bars reach new heights when served slightly warm with a scoop of vanilla ice cream. The contrast between the cool cream and the warm, tangy filling creates an unforgettable dessert experience. For brunch service, skip the glaze and dust with powdered sugar instead for a lighter finish. These bars also pair wonderfully with afternoon tea, especially with Earl Grey or a light floral blend.
Frequently Asked Questions
- → How do I achieve a vibrant red color in rhubarb?
Soak the rhubarb in grenadine syrup for 1-2 hours or overnight. This helps to naturally enhance its ruby red hue.
- → Can I omit the lemon juice and zest?
Yes, lemon juice and zest are optional. They add brightness to the flavor but can be skipped if you prefer the natural taste of rhubarb.
- → Can I use frozen rhubarb for this dessert?
Yes, frozen rhubarb works well. Just thaw and drain it thoroughly before using to avoid excess moisture in the filling.
- → What size pan works best for this dessert?
Use an 8x8 or 9x9 inch square pan for ideal thickness and even baking.
- → Do I need to chill the dough before baking?
Chilling the dough for 10-20 minutes before baking improves the texture, making the crust tender and flaky.
- → What can I substitute if I don’t have grenadine?
You can skip the grenadine and add extra sugar to the rhubarb filling for sweetness. The red color will be less intense but the flavor will still be delicious.