For a sublime pairing, serve a warm rhubarb crumble bar alongside a scoop of vanilla bean ice cream that slowly melts into the crumbly crevices. The contrast of temperatures and textures makes each bite a small event. It reminds me of the first rhubarb stalks my grandma would pull from her garden each spring, their tartness a promise of the sweet treats to come. She’d bake them into pies and crisps, filling the kitchen with a scent that felt like the official start of warmer days.
Those memories are exactly why I love these Rhubarb Crumble Bars. They capture that classic, nostalgic flavor but in a format that’s so much easier to share. No fussing with pie crusts or worrying about a soggy bottom. Just a buttery shortbread base, a layer of sweet-tart rhubarb filling, and that irresistible oat crumble topping we all fight over. It’s the kind of dessert that feels special enough for a holiday table but simple enough for a casual weeknight. Whether you’re looking for delightful march desserts, planning ahead for summer dessert recipes, or need a show-stopping option for your easter desserts recipes, these bars are your answer. Simple ingredients, warm memories.
Table of Contents
Rhubarb Crumble Bars
These bars capture the classic sweet-tart flavor of rhubarb in an easy, shareable format. They feature a buttery oat shortbread base, a juicy rhubarb filling, and a crisp crumble topping. Perfect for spring and summer gatherings or as a nostalgic treat.
- Prep Time: 20min
- Cook Time: 45min
- Total Time: 1h 5min plus cooling
- Yield: 9-12 bars 1x
- Category: dessert
- Method: baking
- Cuisine: American
Ingredients
- 2 cups all-purpose flour
- 1 cup old-fashioned rolled oats
- 1 cup packed light brown sugar
- ½ teaspoon baking soda
- ½ teaspoon salt
- 1 cup (2 sticks) unsalted butter, melted and slightly cooled
- 4 cups fresh rhubarb, chopped into ½-inch pieces
- ½ cup granulated sugar
- 2 tablespoons cornstarch
- 1 tablespoon lemon juice
- 1 teaspoon vanilla extract
Instructions
- Preheat oven to 350°F (175°C). Line an 8x8 or 9x9 inch baking pan with parchment paper, leaving an overhang on two sides.
- In a large bowl, whisk together flour, oats, brown sugar, baking soda, and salt. Pour melted butter over dry ingredients and mix until evenly moist and crumbly.
- Set aside 1 ½ cups of the crumble mixture for the topping. Press the remaining mixture firmly and evenly into the bottom of the prepared pan.
- In a separate bowl, toss chopped rhubarb with granulated sugar, cornstarch, lemon juice, and vanilla extract. Let sit for 5 minutes.
- Spread the rhubarb filling evenly over the pressed crust. Sprinkle the reserved crumble topping over the rhubarb in clumps.
- Bake for 40-50 minutes, until topping is deep golden brown and filling is bubbling at the edges.
- Place pan on a wire rack and let cool completely in the pan before slicing, about 2 hours.
Notes
For frozen rhubarb, thaw and drain well. Do not skip the cornstarch or cut the bars while warm. Bars can be stored at room temperature for 2 days, refrigerated for 5 days, or frozen for up to 3 months.
Nutrition
- Serving Size: 9
- Calories: 280
- Sugar: 24
- Sodium: 150
- Fat: 12
- Saturated Fat: 7
- Unsaturated Fat: 4
- Trans Fat: 0
- Carbohydrates: 42
- Fiber: 2
- Protein: 3
- Cholesterol: 30
Ingredients List
Rhubarb Crumble Bars come together with a straightforward list of ingredients, many of which you likely have in your pantry right now. The magic is in how they layer together.
For the Crust & Crumble Topping:
- 2 cups all-purpose flour
- 1 cup old-fashioned rolled oats
- 1 cup packed light brown sugar
- ½ teaspoon baking soda
- ½ teaspoon salt
- 1 cup (2 sticks) unsalted butter, melted and slightly cooled
For the Rhubarb Filling:
- 4 cups fresh rhubarb, chopped into ½-inch pieces
- ½ cup granulated sugar
- 2 tablespoons cornstarch
- 1 tablespoon lemon juice
- 1 teaspoon vanilla extract
Smart Swaps & Notes:
- Gluten-Free: Use a 1:1 gluten-free flour blend and certified gluten-free oats.
- Dairy-Free: Swap the butter for a high-quality vegan butter stick.
- Frozen Rhubarb: No fresh rhubarb? Frozen works perfectly! Thaw and drain it well to remove excess liquid before using.
- Sugar Adjustment: If your rhubarb is very tart or you prefer a sweeter bar, you can increase the sugar in the filling by 1-2 tablespoons.
Timing
One of the best parts of this rhubarb dessert is how hands-off it is. You get impressive results without being tied to the kitchen.
- Prep Time: 20 minutes
- Cook Time: 45 minutes
- Total Time: 1 hour 5 minutes (plus cooling)
- Most of the work is in the simple chopping and mixing. The oven does the heavy lifting, giving you time to clean up or simply enjoy the aroma. It’s about 30% faster than making a full rhubarb pie from scratch.
Step-by-Step Instructions
Making these bars is a joy, not a chore. We’ll build them in three simple layers: the base, the filling, and the crumble.
1. Prep and Preheat. Start by preheating your oven to 350°F (175°C). Line an 8×8 or 9×9 inch baking pan with parchment paper, leaving an overhang on two sides. This “sling” will make lifting the entire slab of Rhubarb Crumble Bars out for clean cutting a breeze.
2. Make the Crust & Crumble Mixture. In a large bowl, whisk together the flour, oats, brown sugar, baking soda, and salt. Pour the melted, slightly cooled butter over the dry ingredients. Use a fork or your hands to mix until everything is evenly moistened and crumbly. The mixture will hold together when pinched. This one bowl mixture does double duty!
3. Press the Base. Set aside about 1 ½ cups of the crumble mixture for the topping. Press the remaining mixture firmly and evenly into the bottom of your prepared pan. I like to use the bottom of a measuring cup to really pack it down. This creates a solid foundation for our juicy filling.
4. Prepare the Rhubarb Filling. In another bowl, toss the chopped rhubarb with granulated sugar, cornstarch, lemon juice, and vanilla extract. The cornstarch is crucial—it thickens the natural juices from the rhubarb as it bakes, preventing a runny filling. Let this sit for 5 minutes while you tidy up.
5. Assemble the Bars. Spread the rhubarb filling evenly over the pressed crust. Sprinkle the reserved crumble topping over the rhubarb layer, breaking it into small clumps with your fingers for the best texture.
6. Bake to Perfection. Bake for 40-50 minutes, or until the topping is a deep golden brown and the filling is bubbling actively around the edges. The smell will be incredible. Place the pan on a wire rack and let the Rhubarb Crumble Bars cool completely in the pan—this is non-negotiable for clean slices. It usually takes about 2 hours.
Nutritional Information
A serving (one bar) provides approximately:
- Calories: ~280
- Fat: 12g
- Carbohydrates: 42g
- Fiber: 2g
- Sugar: 24g
- Protein: 3g
Rhubarb itself is a good source of Vitamin K and fiber. Using whole rolled oats adds a bit of soluble fiber to the crumble, which is great for digestion. As with any dessert, these bars are a treat to be enjoyed in the context of a balanced diet.
Equipment Needed
You don’t need any fancy gadgets to make these Rhubarb Crumble Bars. A regular kitchen, regular time, great results.
- 8×8 or 9×9 inch Baking Pan: The classic square pan is perfect for bar desserts.
- Parchment Paper: For easy removal and cleanup.
- Large Mixing Bowls (2): One for the crumble, one for the filling.
- Measuring Cups & Spoons
- Rubber Spatula or Fork for mixing.
- Wire Rack for cooling.
Why You’ll Love This Recipe
These Rhubarb Crumble Bars are more than just a dessert; they’re a reliable kitchen friend.
- Comfort Food, Made Easy. All the cozy flavor of a rhubarb crisp, but in a portable, no-plate-required bar. Perfect for picnics, potlucks, or just keeping on the counter for a sweet bite.
- One-Bowl Crumble. The same mixture forms both the buttery crust and the irresistible oat topping. Less mess, more flavor.
- Celebrates the Seasons. It’s the perfect way to use up a bounty of spring or early summer rhubarb. It freezes beautifully, so you can enjoy a taste of summer all year round.
- Crowd-Pleasing Versatility. Equally at home at a fancy brunch, a family barbecue, or as a lunchbox treat. For other bar-style favorites, check out our Mixed Berry Cheesecake Crumb Bars or these fun Lucky Charms Marshmallow Bars.
Healthier Alternatives for the Recipe
Want to lighten things up a bit? You can easily adapt these Rhubarb Crumble Bars.
- Gluten-Free: As mentioned, use a gluten-free flour blend and oats.
- Dairy-Free: A plant-based butter works wonderfully here.
- Reduced Sugar: You can decrease the brown sugar in the crumble by ¼ cup and use a sugar substitute like monk fruit blend in the filling. The tartness of the rhubarb will shine through more.
- Whole Grain: Substitute up to half of the all-purpose flour with whole wheat flour for added fiber and a nuttier flavor.
Serving Suggestions
The beauty of these bars is how they adapt to any occasion.
- The Classic: Warm, with a scoop of vanilla ice cream or a dollop of freshly whipped cream. The contrast is everything.
- Brunch Style: Serve at room temperature with a cup of coffee or tea. They make a fantastic addition to a spread of easter desserts recipes.
- Fancy Touch: Dust with a little powdered sugar just before serving for a pretty finish.
- À la Mode: A scoop of strawberry or ginger ice cream pairs magically with the rhubarb.
- For more bar dessert inspiration, our Mint Chocolate Chip Cookie Bars and Red Velvet Cheesecake Bars are always a hit.
Common Mistakes to Avoid
A few simple tips will guarantee perfect Rhubarb Crumble Bars every single time.
- Skipping the Cornstarch. This is your thickening agent. Without it, the rhubarb filling will be soupy and make the bottom crust soggy.
- Not Draining Frozen Rhubarb. If using frozen, thaw completely and squeeze out the excess liquid in a clean kitchen towel. Too much moisture leads to a wet filling.
- Cutting While Warm. I know it’s hard to wait, but if you cut into these bars before they’re fully cooled, the filling will ooze out and the layers won’t hold their shape. Patience is key.
- Packing the Topping Too Tight. When sprinkling the reserved crumble, just let it fall loosely and clump naturally. Don’t press it down. This creates that delightful, crispy-crunchy texture we love.
Storing Tips for the Recipe
These bars keep wonderfully, making them a fantastic make-ahead treat.
- Room Temperature: Store in an airtight container at room temperature for up to 2 days.
- Refrigerator: For longer storage, keep them in the fridge for up to 5 days. The chilled texture is lovely and firm.
- Freezer: These Rhubarb Crumble Bars freeze exceptionally well. Cool completely, then wrap the whole slab or individual bars tightly in plastic wrap and place in a freezer bag. Freeze for up to 3 months. Thaw overnight in the fridge or at room temperature for a few hours.
- Reheating: For that fresh-from-the-oven feel, warm individual bars in the microwave for 15-20 seconds or in a 300°F oven for 5-10 minutes.
Conclusion
At the end of the day, these Rhubarb Crumble Bars are about more than just a sweet treat. They’re about capturing a fleeting seasonal flavor, creating something beautiful with your hands, and sharing that homemade joy with the people you love. They prove that impressive desserts don’t have to be complicated. With a simple list of ingredients and a little patience for cooling, you can create a dessert that feels like home.
I hope this recipe finds its way into your spring and summer rotation, becoming a new favorite for family dinners, picnics, and quiet moments with a cup of tea. If you’re looking for other easy, bar-style desserts, don’t miss our Mint Chocolate Cookie Bars for a cool, minty twist.
Now, I’d love to hear from you! Did you use fresh or frozen rhubarb? What’s your favorite way to serve them? Let me know how your Rhubarb Crumble Bars turned out in the comments below! And if you share a photo, don’t forget to tag @StackSipSnack so I can see your delicious creation. Happy baking.
Okay, here's the RankMath-compatible FAQ block for Rhubarb Crumble Bars, based on popular "People Also Ask" questions:
FAQs about Rhubarb Crumble Bars
Can rhubarb crumble bars be frozen?
Yes, Rhubarb Crumble Bars freeze well! Let them cool completely, then wrap them tightly in plastic wrap and foil, or store in an airtight container. They can be frozen for up to 2-3 months. Thaw in the refrigerator before serving.
What is the best way to store rhubarb crumble bars?
Store Rhubarb Crumble Bars in an airtight container at room temperature for up to 3 days or in the refrigerator for up to 5 days. Storing in the refrigerator will help them last longer, especially if the weather is warm.
Can I use frozen rhubarb for Rhubarb Crumble Bars?
Absolutely! Frozen rhubarb works perfectly in Rhubarb Crumble Bars. There's no need to thaw it beforehand; simply add it to the recipe as directed. You might need to bake for a few extra minutes.
How do you keep crumble topping crispy?
To keep the crumble topping crispy, don't overmix it, and use cold butter. Avoid overbaking, which can dry it out. Let the bars cool completely on a wire rack, allowing air to circulate and prevent the topping from becoming soggy.
What's the difference between crumble and crisp?
While often used interchangeably, a crumble typically contains only flour, butter, and sugar, creating a more dense topping. A crisp often includes oats and nuts, resulting in a more textured and crunchy topping.
What other fruits can I use with rhubarb in a crumble?
Rhubarb pairs beautifully with other fruits! Strawberry, raspberry, apple, and ginger are all excellent choices. Adjust the sugar level depending on the sweetness of the fruit you choose.
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