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Old-Fashioned Strawberry Rhubarb Bars with Oat Crumble
If you’re looking for a dessert that tastes like spring in every bite, these strawberry rhubarb crumble bars deliver the perfect balance of sweet and tangy.
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These strawberry rhubarb crumble bars are perfect for a quick breakfast, an easy snack on the go, or a batch-made dessert (just add a scoop of vanilla ice cream). The bars have a crumbly oat-based crust with a jammy, fruit filling. Sweet, juicy strawberries balance the sharp, tangy bite of rhubarb – two springtime favorites that hit their peak around the same time. A touch of vanilla adds warmth and complexity, rounding out the tartness and enhancing the berries’ natural sweetness for a nostalgic, flavor-packed bite.
Swap out any of your favorite fruit – I love using a combination of blueberries, blackberries and strawberries as well. For another fruity favorite, try this mixed berry galette.
Why You Will Love This Recipe
- Seasonal and fresh – This recipe uses peak-season fruit for a delicious and flavorful combination.
- Quick and easy – The filling and crust come together quickly before the bars are baked.
- Versatile treat – Perfect as a grab-and-go breakfast, afternoon snack, or casual dessert the whole family will love.
Key Ingredients in This Recipe
- Strawberry – Strawberries have a natural sweetness that perfectly balances the tart and tangy rhubarb.
- Rhubarb – The prime season for rhubarb is from April to early June, and when purchasing it look for firm, crisp stalks that look shiny. This is the perfect recipe to make when you can find some rhubarb!
- Sugar – Letting the fruit sit in the sugar helps to draw out the juices, sweetening the filling.
- Cornstarch – As the fruit filling cooks, it releases a lot of water, and the cornstarch acts to bind it together so it doesn’t become too runny.
- Lemon – I use both the lemon juice and zest in this recipe. The zest has a more concentrated bright lemon flavor.
- Vanilla – Vanilla’s creamy notes help to round out the flavors of both the strawberry and rhubarb.
- Flour – All-purpose flour is the base of the crumble topping.
- Oats – The crumble crust is made from a combination of both old fashioned oats (not quick-cook oats) and flour.
- Butter – The butter is cut into the crumble mixture forming small crumbs so as it cooks it melts forming a buttery crust.
A full ingredient list with exact amounts can be found in the recipe card below.
Swaps and substitutions
- To make these bars when rhubarb is out of season, substitute with an additional cup of diced strawberries.
- The strawberries and rhubarb can also be swapped for 4½ cups (540g) of another diced fruit like halved blackberries, raspberries or whole blueberries.
- If you don’t want to lift the bars out of the pan before serving, you can forgo the parchment paper.
How to Make Strawberry Rhubarb Bars
In a medium bowl, mix the strawberries, rhubarb, sugar, cornstarch, vanilla, lemon zest, and juice. Let sit for 10 minutes.
Preheat the oven to 350ºF (180ºC). In a large bowl, stir together the flour, oats, sugar, baking powder, salt, and cinnamon. Add the egg and cold butter pieces, then use your hands or a pastry cutter to work the butter into the mix until crumbly.
Lightly grease a 9×13” baking dish and line with parchment. Press half the crumble mixture evenly into the bottom. Spoon the fruit and any juices on top, then sprinkle the rest of the crumble over it.
Bake for 55 to 60 minutes, until bubbly and golden. Cool completely before slicing into bars.
How to Store These Bars
Let the bars cool completely before storing. Store in an airtight container for up to 4 days.
Can You Use Frozen Fruit?
Frozen fruit will work in this recipe. I recommend thawing the fruit and draining any excess liquid before substituting it for the fresh fruit.
FAQ – Frequently Asked Questions
Can I use another fruit to make oat crumble bars?
Swap out any of your favorite fruit – I love using a combination of blueberries, blackberries and strawberries as well.
Can I use frozen fruit?
Yes! Frozen fruit works well—just thaw and drain excess liquid to avoid a soggy crust.
Can I make these bars in advance?
Absolutely! These bars keep well and actually slice more cleanly once they’ve cooled. Store in an airtight container for up to 4 days.
Can I freeze strawberry rhubarb bars?
Freeze in a resealable plastic bag for up to 2 months. Let frozen bars thaw in the fridge or at room temperature.
Can I make this recipe gluten-free?
Yes! Substitute the flour with a 1:1 gluten-free flour blend and be sure to use certified gluten-free oats.
Why is there cornstarch in the filling?
Cornstarch helps thicken the fruit juices as the bars bake, so the filling sets properly and isn’t too runny.
Can I serve these bars warm?
Yes! They’re delicious slightly warm, especially with a scoop of vanilla ice cream – but they’ll hold their shape better when cooled.
Give these fruit-forward desserts a try:
Made this dish? Be sure to rate the recipe and drop a comment below! Your feedback means everything (and helps others find it too)!
Old-Fashioned Strawberry Rhubarb Bars with Oat Crumble
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Ingredients:
For the filling:
- 3½ cups diced strawberries
- 1½ cups diced rhubarb
- ½ cup granulated sugar
- 2 tablespoons cornstarch
- 2 teaspoons vanilla extract
- 1 teaspoon lemon zest
- 2 tablespoons freshly squeezed lemon juice
For the crumble:
- 2 cups all-purpose flour
- 1 cup old-fashioned oats
- 1 cup granulated sugar
- 1 teaspoon baking powder
- ½ teaspoon kosher salt
- ½ teaspoon ground cinnamon
- 1 large egg
- 1 cup butter, chilled, and cut into ½” pieces
Instructions:
For the filling:
- In a medium mixing bowl, combine the strawberries, rhubarb, sugar, cornstarch, vanilla, lemon zest and lemon juice. Stir together and let sit for 10 minutes.
For the crumble:
- Preheat oven to 350ºF (180ºC).
- In a large mixing bowl, stir together the flour, oats, sugar, baking powder, salt and cinnamon. Add the egg and chilled pieces of butter. Use a pastry cutter or your hands to cut the butter into the flour mixture until pea-size pieces form. The mixture will be dry and crumbly.
- Lightly grease a 9”x13” (23cm x 33cm) baking dish, then line with parchment paper (to help lift the bars out later). Divide half the crumble mixture into the pan, gently pressing it evenly to the edges. Spread the fruit filling (and any juices) over the top. Scatter the remaining crumble mixture over the top.
- Bake until the mixture is bubbling and the crumble topping is golden brown, about 55 to 60 minutes. Let cool completely, then remove from the pan and cut into bars. Serve warm or at room temperature.
Notes:
- To make these bars when rhubarb is out of season, substitute with an additional cup of diced strawberries.
- The strawberries and rhubarb can also be swapped for 4½ cups (540g) of another diced fruit like halved blackberries, raspberries or whole blueberries.
Nutrition:
Calories: 351kcal | Carbohydrates: 49g | Protein: 4g | Fat: 16g | Saturated Fat: 10g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 1g | Cholesterol: 54mg | Sodium: 262mg | Potassium: 158mg | Fiber: 2g | Sugar: 27g | Vitamin A: 514IU | Vitamin C: 27mg | Calcium: 53mg | Iron: 1mg
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I finally found some rhubarb at the grocery store the other day and made these strawberry rhubarb bars. They were a huge hit and didn’t last long after everyone had the first bite. Trying the mixed berry ones next!
So happy to hear they were a hit!!
My whole family, including two toddlers, loves these bars. I subbed mixed berries for the fruit layer and vegan butter and it turned out great. We love them hot or cold!
So happy you were able to make substitutions that worked well for your family! And love the mixed berry variation too!
Love this recipe! So easy to switch up depending on what’s in season/what you have/what you need to use up. I made them this weekend with a canned cherry filling (added some cherry jam, lemon zest and vanilla) and sprinkled the top with sliced almonds- so yummy!
I can’t wait to try it with cherry and sliced almonds! Thanks for sharing this variation!! It sounds so good.
We used to grow our own rhubarb so it was a treat to find this rhubarb recipe and find it so enjoyable!