SPREAD LOVE

Strawberry Rhubarb Crumble Bars

Name: Strawberry Rhubarb Crumble Bars
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Cuisine: American
Ingredients: Cooking spray; 3 cups all-purpose flour; 1 1/2 cups old-fashioned rolled oats; 1 cup packed light brown sugar; 1 tsp baking powder; 1 tsp kosher salt; 1 1/2 cups unsalted butter, cold, cubed; 2 large eggs; 2 Tbsp whole milk; 3 cups fresh strawberries, hulled, cut into 1/2″ pieces; 3 cups frozen rhubarb, thawed, drained, pressed dry, sliced 1/4″ thick; 1/3 cup granulated sugar; 1 Tbsp cornstarch; 1 Tbsp fresh lemon juice

There’s something about the first spring strawberries and tart stalks of rhubarb that takes me right back to lazy afternoons in my grandmother’s kitchen — the smell of butter and brown sugar, the sound of a fork scraping a pan as she cut generous squares to share. These Strawberry Rhubarb Crumble Bars blend bright, tangy fruit with an oat-and-brown-sugar crumb for a dessert that’s both homey and a little fancy. If you enjoy a tender oat crust with a juicy fruit filling, try this twist on classic crumble bars and compare it to a similar oat-crumble treat like strawberry oatmeal crumble bars for another comforting option.

Why make this recipe
If you’re tired of overly sweet, fussy desserts, this recipe is perfect because it balances tart rhubarb and bright strawberries with a crunchy oat crumble that’s simple to assemble yet impressive to serve. It’s a great way to use spring fruits and make something that feels homemade without taking all afternoon. Plus, it freezes beautifully so you can enjoy a bright bite of summer any time.

Step-by-Step Guide to Making Strawberry Rhubarb Crumble Bars

Below is an expanded, easy-to-follow version of the original directions that walks you through each step, offers small technique tips, and helps you troubleshoot as you go.

Prep and preheat

Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with cooking spray so the bars release cleanly after baking.

Make the crumble base

In a large mixing bowl, whisk together 3 cups all-purpose flour, 1 1/2 cups old-fashioned rolled oats, 1 cup packed light brown sugar, 1 teaspoon baking powder, and 1 teaspoon kosher salt.
Add 1 1/2 cups cold, cubed unsalted butter. Use a pastry cutter, two knives, or your fingertips to cut the butter into the dry ingredients until the mixture becomes sandy and crumbly with pea-sized bits of butter visible. This bit of texture helps create a tender but sturdy crust.
Stir in 2 large eggs and 2 tablespoons whole milk until the dough comes together; a few crumbs are okay. Reserve about 1 1/2 cups of the crumble mixture for the topping and press the remaining mixture into the bottom of the prepared 9×13 pan to form an even crust.

Prepare the fruit filling

In another bowl, combine 3 cups fresh strawberries (hulled and cut into 1/2″ pieces) and 3 cups thawed, drained, and pressed-dry frozen rhubarb (sliced 1/4″ thick).
Add 1/3 cup granulated sugar, 1 tablespoon cornstarch, and 1 tablespoon fresh lemon juice. Mix gently so the fruit is evenly coated but not mashed. The cornstarch will help thicken juices released during baking.

Assemble the bars

Spread the fruit filling evenly over the pressed crust. Try not to pile it too high; an even layer bakes more uniformly.
Sprinkle the reserved 1 1/2 cups of crumble mixture evenly over the fruit to create a crisp, golden topping.

Bake

Place the pan in the preheated oven and bake for 35–40 minutes, or until the top is golden brown and the filling is bubbling at the edges. If the topping is browning too quickly but the filling isn’t bubbling yet, tent the pan loosely with foil for the remainder of the bake.

Cool and cut

Remove the bars from the oven and let them cool completely in the pan on a wire rack. Full cooling is important: warm fruit bars will be very soft and can fall apart when you cut them.
Once chilled, lift the slab from the pan if you used parchment or carefully cut into squares with a sharp knife for serving.

Directions (concise original steps for quick reference):
Preheat oven to 350°F (175°C). Grease a 9×13 inch baking dish with cooking spray. In a bowl, combine flour, oats, brown sugar, baking powder, and salt. Add cubed butter, mix until crumbly. Stir in eggs and milk until combined. Reserve 1 1/2 cups for topping. In another bowl, mix strawberries, rhubarb, granulated sugar, cornstarch, and lemon juice. Press remaining mixture into the baking dish. Spread fruit filling over crust, then sprinkle reserved crumb on top. Bake for 35-40 minutes until golden and filling is bubbling. Cool completely before cutting.

Ingredients

Cooking spray
3 cups all-purpose flour
1 1/2 cups old-fashioned rolled oats
1 cup packed light brown sugar
1 tsp baking powder
1 tsp kosher salt
1 1/2 cups unsalted butter, cold, cubed
2 large eggs
2 Tbsp whole milk
3 cups fresh strawberries, hulled, cut into 1/2″ pieces
3 cups frozen rhubarb, thawed, drained, pressed dry, sliced 1/4″ thick
1/3 cup granulated sugar
1 Tbsp cornstarch
1 Tbsp fresh lemon juice

Best Way to Store Strawberry Rhubarb Crumble Bars

Room temperature: Store loosely covered at room temperature for up to 24 hours in a cool place (avoid direct sunlight).
Refrigerator: Place in an airtight container and refrigerate for 3–5 days at about 35–40°F (2–4°C).
Freezer: Wrap bars individually in plastic wrap and store in a freezer-safe container or bag for up to 3 months. Thaw in the refrigerator overnight and reheat briefly in a 325°F oven to revive the crisp topping.

Serving Ideas for Strawberry Rhubarb Crumble Bars

Warm with vanilla: Serve a square slightly warmed with a scoop of vanilla ice cream or a dollop of lightly whipped cream for a classic dessert.
Brunch-friendly: Cut into smaller bars and serve alongside coffee or tea for an elevated brunch offering. The tart fruit and oat topping pair well with a balanced breakfast spread.
Picnic-friendly: Because they travel well, wrap bars individually for picnics or potlucks. Keep them chilled until serving for the best texture.

tips to make Strawberry Rhubarb Crumble Bars
Q: How do I keep the crust from becoming soggy under the fruit?
A: Make sure to press the bottom crust firmly and evenly into the pan so it forms a compact barrier. Also, toss the fruit with cornstarch to absorb excess juice during baking.

Q: How do I get the crumble topping extra golden?
A: For a deeper golden color, give the top a light sprinkle (about 1–2 teaspoons) of granulated sugar before baking to promote caramelization on the exposed crumbs.

Q: Can I use fresh rhubarb instead of frozen?
A: Yes — chop fresh rhubarb into 1/4″ pieces and toss with the sugar and cornstarch as directed. If the rhubarb is especially watery, let it sit for 10 minutes to macerate, then drain briefly.

variation (if any)

Swap the oats: For a nuttier crumb, replace 1/2 cup of the rolled oats with 1/2 cup finely chopped almonds or walnuts; they’ll toast in the oven and add texture.
Another easy substitution is to replace half the strawberries with raspberries or blueberries for a different fruit medley — keep the cornstarch amount the same if you use more juicy berries.

FAQs
Q: Can I make these bars ahead of time?
A: Yes — bake and cool completely, then store layered between pieces of parchment in an airtight container in the fridge for up to five days. These make great make-ahead desserts for gatherings.

Q: Do I have to use cornstarch in the filling?
A: Cornstarch helps thicken the fruit juices as they bake so the bars hold together better. If you prefer, you can substitute 1 tablespoon of tapioca starch instead.

Q: How do I cut neat squares?
A: Chill the baked slab thoroughly (several hours or overnight) before cutting. Warm bars are more likely to crumble. Use a sharp chef’s knife and wipe it clean between cuts for tidy edges.

Q: Can I reduce sugar in the recipe?
A: Yes — you can cut the granulated sugar in the filling by 25% if you prefer a tarter result, especially if using very sweet strawberries. Taste the fruit mix first if you can.

Q: What if the topping isn’t crisp after baking?
A: If the filling is still juicy but the top isn’t crisp, return the pan to a 350°F oven for 5–10 minutes uncovered. Let the bars cool fully before slicing to allow the filling to set.

Final notes and technique pointers

Work quickly with the butter: Cold, cubed butter yields the best crumb texture. If the butter gets too warm, pop the bowl in the fridge for 10 minutes before proceeding.
Drain well: Especially when using frozen rhubarb, press the thawed pieces between paper towels to remove excess moisture; this prevents a soggy bottom layer.
Slice with care: For the cleanest presentation, chill the bars completely and use a hot, dry knife (dip it briefly in hot water, dry, then slice).

Conclusion

If you’d like another take on these fruity, crisp bars, see the Cooking Classy strawberry rhubarb bars (with crumb topping) for a closely related crumb-bar approach and inspiration. For a slightly different crumb-bar technique and variation ideas, check out Sally’s Baking Addiction’s strawberry rhubarb crumb bars.