Old-Fashioned Strawberry Rhubarb Bars are the kind of bake I reach for when I want a simple dessert that still feels special. You get a buttery oat crumble on top and bottom, with a jammy strawberry-rhubarb layer in the middle.
I like how these slice into neat squares once they’re chilled, and the flavor is exactly what I want from strawberry rhubarb: sweet-tart, a little bright from lemon, and not heavy. The crumble is sturdy but still has that soft, crumbly bite from the oats.
These are especially good for weekend baking, potlucks, and cookie trays when you want something that travels well. I usually serve them plain, but a little powdered sugar or a scoop of vanilla ice cream is always a good idea.
Why You’ll Love This Recipe
Old-fashioned in the best way: It’s a straightforward crumble bar with a fruit filling that tastes like summer, even when you make it with frozen fruit.
That jammy center: The cornstarch thickens the strawberries and rhubarb into a sliceable, sticky filling that doesn’t run all over the pan.
Buttery oat crumble: The crust and topping are the same mixture, so there’s no fussing with separate layers.
Easy to slice neatly: A full cool-down and a short chill makes a big difference, and you’ll get clean bars instead of a soft scoop.
Works for lots of pans: Make it in an 8×8 or 9×9, or double it for a 9×13 when you need more.
Ingredients You’ll Need
Strawberry Rhubarb Filling
- Strawberries: Fresh is great, but frozen works too if you thaw and drain well. I like chopping them so the filling turns more jammy than chunky.
- Rhubarb: Dice it fairly small so it softens in the bake time. If your stalks are very thick, a smaller dice helps a lot.
- Granulated sugar: Rhubarb needs it, and it also helps pull out juices so the filling cooks down nicely.
- Cornstarch: This is what thickens the fruit juices into a sliceable layer. If your fruit is extra juicy, bump it up a bit.
- Lemon juice: A little acidity keeps the filling tasting bright and not flat.
- Vanilla extract: Just enough to round out the fruit and make it taste more like a dessert bar than a plain compote.
- Salt: Don’t skip it; it keeps the filling from tasting overly sweet.
Crust And Crumble
- All-purpose flour: I use regular flour here. It gives the crumble enough structure so the bottom bakes up sturdy.
- Old fashioned rolled oats: These give you that classic chew and texture. Quick oats work in a pinch, but the bars won’t be quite as hearty.
- Light brown sugar: Adds a deeper sweetness and helps the crumble hold together. Dark brown sugar works too if that’s what you have.
- Baking powder: Just a little lift so the crust doesn’t bake up too dense.
- Ground cinnamon (optional): I like a small pinch here, especially if the strawberries aren’t super flavorful. You can leave it out if you want the fruit to be the main thing.
- Salt: Helps the crust taste like more than just sweet crumbs.
- Unsalted butter: Melted butter makes this easy and fast. Let it cool slightly so it mixes in evenly and doesn’t feel greasy.
Optional Finish
- Powdered sugar: A light dusting is pretty and keeps the bars feeling “old-fashioned bake sale” in a good way.
- Vanilla ice cream: Great if you’re serving these as dessert instead of an afternoon snack.
Recipe Instructions
- Preheat the oven: Heat the oven to 350°F. Line an 8×8-inch or 9×9-inch pan with parchment paper and lightly grease it.
- Mix the dry ingredients: In a medium bowl, whisk together the flour, oats, brown sugar, baking powder, cinnamon (if using), and salt.
- Add the butter: Stir in the melted butter until the mixture turns clumpy and you don’t see dry flour.
- Press the crust: Press about two thirds of the oat mixture firmly into the prepared pan to form an even crust.
- Mix the filling: In another bowl, toss the strawberries, rhubarb, granulated sugar, cornstarch, lemon juice, vanilla, and salt until evenly coated.
- Add the filling: Spread the fruit mixture evenly over the crust, getting it into the corners.
- Top with crumble: Sprinkle the remaining crumble evenly over the filling and lightly press it down so it holds together as it bakes.
- Bake: Bake for 40 to 50 minutes, until the top is golden brown and the filling is bubbling.
- Cool and chill: Cool completely at room temperature, then chill for 1 to 2 hours for clean slices.
- Slice and serve: Lift out using the parchment, cut into bars, and dust with powdered sugar or serve with vanilla ice cream if you like.
Some of my tips!
This is the part that really makes a difference. If you only read one section, make it this one because this is where I share the little trick that helps the recipe turn out so well.
Recipe Tips & Tricks
Use parchment paper. It makes it easy to lift the whole slab out of the pan, and it saves you from fighting sticky edges if a little filling bubbles up.
Dice the rhubarb small. Bigger pieces can stay a little firm, especially if your stalks are thick. A small dice bakes up tender and more jam-like.
Watch for bubbling filling. Golden top is nice, but the real sign is the filling bubbling across the center, not just at the edges.
Cool completely before chilling. If you chill while the pan is still warm, the crust can get a little soggy. Let it cool down first, then refrigerate for the cleanest cuts.
Adjust cornstarch for juicy fruit. Some strawberries throw off a lot of liquid, especially frozen ones. If it looks very wet in the bowl, use a bit more cornstarch so the bars set up well.
Make some touches!
There are plenty of easy ways to serve this depending on the occasion. Keep it simple, or add a few small touches to make it feel a little more special.
Serving Suggestions
- Powdered sugar: Dust the top right before serving. It makes them look finished without adding much sweetness.
- Vanilla ice cream: Serve a bar with a scoop on the side if you’re doing dessert. I like letting the ice cream melt a little into the crumble.
- Whipped cream: A spoonful of lightly sweetened whipped cream is nice if you want something softer than ice cream. A tiny bit of lemon zest on top is good too.
- Fresh berries: Add a few sliced strawberries on the plate when they’re in season. It keeps everything feeling bright and simple.
- Coffee or tea: These are really good with coffee in the afternoon, or with a plain black tea if you want something not too rich.
Save it for later
This section covers how to store leftovers and what parts of the recipe you can prepare ahead of time.
Storage and Make Ahead
Store leftovers covered in the fridge for up to 4 days. I like them cold, but you can also let a bar sit at room temp for 10 to 15 minutes if you want the crust a little softer.
You can make this recipe ahead for gatherings since it slices best after chilling anyway. Bake it the day before, chill, then cut right before you’re ready to set it out.
If you want them to last longer, freeze individual portions in an airtight container. Thaw in the fridge overnight so the filling doesn’t get watery.
For a warm bar, microwave a piece briefly just until it’s no longer cold. It will be softer and a little more messy, but still very good.
A few quick answers
This section covers a few extra details that may help before you head to the recipe card.
Recipe FAQs
Can I use frozen strawberries and rhubarb?
Yes. Thaw the fruit first and drain it well so you’re not adding a lot of extra liquid to the filling. If it still looks very juicy, increase the cornstarch a bit.
How do I know when the bars are done baking?
Look for a golden top and bubbling filling. I like to see bubbling in the center area, not just around the edges.
Why do I need to chill them before slicing?
The filling thickens as it cools, and the butter in the crumble firms up in the fridge. If you cut too soon, the bars will be softer and the filling will smear.
Can I swap in other berries?
Yes. Swapping half the strawberries for raspberries is really good and gives a deeper berry flavor. Just keep an eye on juiciness and adjust cornstarch if needed.
Can I double this recipe for a 9×13-inch pan?
Yes, double everything and bake about 45 to 55 minutes. It’s done when the top is evenly golden and the filling is bubbling.
You might also like
Before you go, take a look at a few other recipes below the recipe card. They use similar ingredients in a different way and are worth saving too.
MORE DINNER RECIPES TO TRY
Old-Fashioned Strawberry Rhubarb Bars
INGREDIENTS
Strawberry Rhubarb Filling
- 2 cups strawberries chopped
- 2 cups rhubarb diced
- 3/4 cup granulated sugar
- 2 tbsp cornstarch
- 1 tbsp lemon juice
- 1 tsp vanilla extract
- 1/8 tsp salt.
Crust And Crumble
- 1 1/2 cups all purpose flour
- 1 cup old fashioned rolled oats
- 1 cup light brown sugar packed
- 1/2 tsp baking powder
- 1/2 tsp ground cinnamon optional
- 1/2 tsp salt
- 1 cup unsalted butter melted and cooled slightly.
Optional Finish
- powdered sugar for dusting
- vanilla ice cream for serving.
INSTRUCTIONS
Prep And Pan
- heat oven to 350 F
- line an 8x8 inch or 9x9 inch pan with parchment and lightly grease.
Make Crust And Crumble
- whisk flour oats brown sugar baking powder cinnamon and salt
- stir in melted butter until clumpy
- press about two thirds of mixture firmly into pan to form an even crust.
Make Filling
- toss strawberries rhubarb sugar cornstarch lemon juice vanilla and salt until evenly coated
- spread filling evenly over crust.
Bake And Cool
- sprinkle remaining crumble evenly over filling and lightly press
- bake until golden brown and filling is bubbling 40 to 50 minutes
- cool completely at room temperature then chill 1 to 2 hours for clean slices
- cut into bars.
