Perfect Strawberry Rhubarb Crisp Bars

Here are my strawberry rhubarb crisp bars, with a buttery oat crumble base, a sweet-tart fruit filling that’s perfectly thick, and a crispy crumb topping.

These bars are what I make when I want all the goodness of a fruit crisp but in an easy-to-serve, hand-held form. They’re perfect for potlucks and picnics, and my kids love grabbing them straight from the fridge for a quick snack.

What Kind of Rhubarb Should I Use?

Fresh rhubarb is your best bet for these crisp bars, and you’ll find it in season during spring and early summer at most grocery stores and farmers markets. The color of the stalks doesn’t really matter – both red and green rhubarb will taste the same, though the red varieties do add a prettier pink hue to your bars. Make sure to trim off and discard any leaves, as they’re toxic, and cut away any brown or dried ends from the stalks. If fresh rhubarb isn’t available, frozen rhubarb works just fine – just don’t thaw it before using, as it can get mushy and release too much liquid into your filling.

Options for Substitutions

This recipe is pretty forgiving, so here are some swaps you can make if needed:

• Whole wheat flour: All-purpose flour works just fine here. You can also try a mix of half whole wheat and half all-purpose if you want something in between.
• Butter: You can use coconut oil as a substitute, but make sure it’s in solid form (chilled). The texture will be slightly different but still tasty.
• Rhubarb: If rhubarb isn’t in season or you can’t find it, try using all strawberries (about 7 cups total) or mix in some raspberries or blueberries. Keep in mind that rhubarb adds a nice tart flavor, so you might want to add a tablespoon of lemon juice to keep that tangy balance.
• Oats: Stick with regular rolled oats for this one – quick oats will get too mushy, and steel-cut oats won’t soften enough. If you need a gluten-free option, make sure to use certified gluten-free oats.
• Corn starch: Tapioca starch or arrowroot powder work as thickeners too. Use the same amount, but note that tapioca can make the filling slightly more gel-like.
• Brown sugar: Regular white sugar plus a tablespoon of molasses will do the trick, or you can use coconut sugar for a less processed option.

Watch Out for These Mistakes While Baking

The biggest mistake with strawberry rhubarb crisp bars is skipping the pre-bake of the bottom crust, which leads to a soggy base that won’t hold up when you try to cut clean squares – those 10-15 minutes make all the difference in getting a firm, cookie-like foundation. Another common error is not letting your fruit mixture sit for a few minutes after mixing, which allows the cornstarch to properly absorb the juices and prevents a runny filling that seeps through the crust. Make sure your butter is cold when making the oat topping so it stays crumbly rather than turning into a dense paste, and always let the bars cool completely in the pan before cutting – warm bars will fall apart no matter how perfectly you baked them. If your fruit seems extra juicy, add an extra tablespoon of cornstarch to the filling to help it set properly.

What to Serve With Strawberry Rhubarb Crisp Bars?

These bars are pretty sweet and rich on their own, so a scoop of vanilla ice cream on top is always a winner – the cold creaminess balances out the tart fruit filling perfectly. You could also serve them with a dollop of whipped cream or Greek yogurt if you want something a bit lighter. I like to pair these bars with a hot cup of coffee or tea for an afternoon snack, and they’re great for potlucks or picnics since they’re easy to grab and go. If you’re serving them for dessert after dinner, consider putting out some fresh berries on the side to keep the fruity theme going.

Storage Instructions

Store: Keep your strawberry rhubarb crisp bars in an airtight container in the fridge for up to 5 days. The filling stays nice and jammy while the topping holds its texture pretty well. I like to cut them into squares first so they’re easy to grab whenever a craving hits.

Freeze: These bars are great for freezing! Wrap individual portions in plastic wrap, then place them in a freezer bag for up to 3 months. You can also freeze the whole pan if you prefer, just make sure it’s wrapped tightly.

Serve: Enjoy these bars straight from the fridge for a cool treat, or let them sit at room temperature for about 20 minutes if you prefer. If you froze them, just thaw in the fridge overnight or at room temperature for an hour or so before digging in.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 3200-3500
• Protein: 28-34 g
• Fat: 85-95 g
• Carbohydrates: 610-660 g

Ingredients

For the crust and topping:

• 1 cup brown sugar (I prefer C&H for consistent moisture)
• 2 cups oats (I use Quaker old fashioned oats for better texture)
• 1 1/4 cups whole wheat flour (I always use King Arthur for a finer crumb)
• 1 cup butter

For the fruit filling:

• 5 cups strawberries (hulled and sliced into 1/4-inch rounds)
• 3 1/2 cups rhubarb (trimmed and cut into 1/2-inch pieces)
• 1/4 cup corn starch (sifted to prevent lumps in the filling)
• 3/4 cup sugar
• 1/2 teaspoon vanilla extract

Step 1: Prepare the Mise en Place and Preheat

• 5 cups strawberries
• 3 1/2 cups rhubarb
• 1/4 cup corn starch

Preheat your oven to 350°F.

While it heats, hull and slice the strawberries into 1/4-inch rounds, then trim the rhubarb and cut it into 1/2-inch pieces.

Sift the corn starch into a small bowl to remove any lumps, which will help create a smooth, evenly thickened filling.

Line a 9×13 inch baking dish with parchment paper for easy removal and cleanup.

Having all your fruit prepped and ready before you start the crust ensures a smooth workflow and prevents the filling from oxidizing.

Step 2: Make the Oat Crust Base

• 1 cup brown sugar
• 2 cups oats
• 1 1/4 cups whole wheat flour
• 1 cup butter

In a large bowl, combine the brown sugar, oats, and whole wheat flour.

Cut the cold butter into small cubes and add it to the dry mixture.

Using your fingers or a pastry cutter, work the butter into the dry ingredients until the mixture resembles coarse breadcrumbs with pea-sized pieces of butter throughout.

I like to keep the butter pieces visible rather than fully incorporated—this creates those beautiful crispy, buttery clusters in the finished bars.

Step 3: Press the Crust and Pre-Bake

• oat crust mixture from Step 2

Reserve 1 cup of the oat mixture in a separate bowl for topping.

Press the remaining oat mixture firmly and evenly into the prepared baking dish, creating an even layer across the bottom.

Bake this crust for 10-15 minutes until it’s set and lightly golden—this par-baking step helps prevent a soggy bottom and gives the crust structure to support the juicy fruit filling.

Step 4: Prepare the Strawberry-Rhubarb Filling

• 5 cups strawberries from Step 1
• 3 1/2 cups rhubarb from Step 1
• 1/4 cup corn starch from Step 1
• 3/4 cup sugar

While the crust bakes, combine the sliced strawberries, rhubarb pieces, sifted corn starch, and sugar in a bowl.

Gently fold the ingredients together until the fruit is evenly coated with the corn starch and sugar mixture.

The sifted corn starch will distribute evenly and thicken the fruit juices as the bars bake, creating a jammy filling rather than a runny one.

Step 5: Assemble and Bake the Bars

• fruit filling from Step 4
• reserved oat mixture from Step 3

Remove the pre-baked crust from the oven and spread the strawberry-rhubarb filling evenly over it.

Sprinkle the reserved 1 cup of oat mixture over the top, breaking it into irregular clusters as you distribute it—these clusters will become the crispy topping.

Return the baking dish to the oven and bake for 40-45 minutes until the fruit is bubbling around the edges and the topping is golden brown.

Step 6: Cool and Cut

Remove the baking dish from the oven and let the bars cool in the pan for at least 30-45 minutes before cutting.

I find that cooling them completely gives cleaner cuts and allows the filling to set up enough so the bars hold their shape.

Once cooled, lift the bars out using the parchment paper overhang and cut into squares using a sharp knife.

Perfect Strawberry Rhubarb Crisp Bars

Delicious Perfect Strawberry Rhubarb Crisp Bars recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 55 minutes mins

Total Time 1 hour hr 20 minutes mins

Servings 24 bars

Calories 3350 kcal

Ingredients

  

For the crust and topping::

• 1 cup brown sugar (I prefer C&H for consistent moisture)
• 2 cups oats (I use Quaker old fashioned oats for better texture)
• 1 1/4 cups whole wheat flour (I always use King Arthur for a finer crumb)
• 1 cup butter

For the fruit filling::

• 5 cups strawberries (hulled and sliced into 1/4-inch rounds)
• 3 1/2 cups rhubarb (trimmed and cut into 1/2-inch pieces)
• 1/4 cup corn starch (sifted to prevent lumps in the filling)
• 3/4 cup sugar
• 1/2 teaspoon vanilla extract

Instructions

 

• Preheat your oven to 350°F. While it heats, hull and slice the strawberries into 1/4-inch rounds, then trim the rhubarb and cut it into 1/2-inch pieces. Sift the corn starch into a small bowl to remove any lumps, which will help create a smooth, evenly thickened filling. Line a 9x13 inch baking dish with parchment paper for easy removal and cleanup. Having all your fruit prepped and ready before you start the crust ensures a smooth workflow and prevents the filling from oxidizing.
• In a large bowl, combine the brown sugar, oats, and whole wheat flour. Cut the cold butter into small cubes and add it to the dry mixture. Using your fingers or a pastry cutter, work the butter into the dry ingredients until the mixture resembles coarse breadcrumbs with pea-sized pieces of butter throughout. I like to keep the butter pieces visible rather than fully incorporated—this creates those beautiful crispy, buttery clusters in the finished bars.
• Reserve 1 cup of the oat mixture in a separate bowl for topping. Press the remaining oat mixture firmly and evenly into the prepared baking dish, creating an even layer across the bottom. Bake this crust for 10-15 minutes until it's set and lightly golden—this par-baking step helps prevent a soggy bottom and gives the crust structure to support the juicy fruit filling.
• While the crust bakes, combine the sliced strawberries, rhubarb pieces, sifted corn starch, and sugar in a bowl. Gently fold the ingredients together until the fruit is evenly coated with the corn starch and sugar mixture. The sifted corn starch will distribute evenly and thicken the fruit juices as the bars bake, creating a jammy filling rather than a runny one.
• Remove the pre-baked crust from the oven and spread the strawberry-rhubarb filling evenly over it. Sprinkle the reserved 1 cup of oat mixture over the top, breaking it into irregular clusters as you distribute it—these clusters will become the crispy topping. Return the baking dish to the oven and bake for 40-45 minutes until the fruit is bubbling around the edges and the topping is golden brown.
• Remove the baking dish from the oven and let the bars cool in the pan for at least 30-45 minutes before cutting. I find that cooling them completely gives cleaner cuts and allows the filling to set up enough so the bars hold their shape. Once cooled, lift the bars out using the parchment paper overhang and cut into squares using a sharp knife.