Simple yet delicious rhubarb bars with a buttery shortbread crust, sweet and tart rhubarb custard filling, and finished with a cinnamon oatmeal streusel topping. All you could ever want in a rhubarb bar! Plus, they're so easy to make!
When creating these rhubarb bars, I wanted them to include all the best things! A thick and buttery crust that would hold up to all the filling, a sweet and tart soft rhubarb center, and lastly a cinnamon streusel crumble topping because no bar is truly complete without it. And these bars are just that - perfection!
I could eat these rhubarb bars for breakfast, lunch, and dinner. They're not overly sweet (just the way I like it) and have just the right amount of tartness from the rhubarb.
If you're looking to mix things up, turn these into strawberry rhubarb bars by swapping a cup of rhubarb with sliced strawberries! Or you could even use raspberries.
Why you'll love these rhubarb bars
- Easy to make. All you need is about 15 minutes of hands-on prep time to make these deliciously sweet and tart rhubarb bars!
- Shortbread crust. Made with a simple but tasty shortbread crust that's firm enough to hold up to all that tasty rhubarb filling.
- Custard rhubarb center. Soft, sweet, and tart rhubarb custard filling that requires minimal ingredients and is quickly mixed up in a bowl - no stovetop cooking!
- Crumble topping. In my opinion, a good bar is always finished with a sweet oatmeal streusel crumble. The final step component making these the perfect rhubarb bars!
- All-purpose flour
- Old fashioned oats
- Granulated sugar
- Brown sugar
- Powdered sugar
- Baking powder
- Heavy whipping cream
- Salted butter
- Vanilla extract
- Rhubarb (fresh or frozen)
Scroll down to the recipe card for complete ingredient list.
How to make rhubarb bars
Making rhubarb bars is a 3 part process that only takes about 15 minutes! I like to use the same bowl to make the crust and filling to save on cleanup.
- Shortbread crust. Start by mixing together dry ingredients then add in the melted butter to create a crumbly shortbread mixture. Make sure you press firmly into the baking dish to create a tight, even crust. I like to use a spatula for this.
- Rhubarb custard filling. Using the same bowl you used to make the crust, mix together your dry ingredients then add in beaten eggs, heavy cream, and vanilla. That's it! So easy. The filling is then poured over the par-baked crust. At this point, you'll bake the bars for 20 minutes to allow the custard filling to start setting up before topping them with the streusel crumble.
- Crumble topping. Mix together your dry ingredients then use a pasty blender or food processor to work in cold butter until everything is combined but crumbly. Store the crumble topping in the fridge to keep cool until it's time to sprinkle over the bars.
- Let cool then slice and enjoy! Because these bars are made with a custard rhubarb filling, it's important to let them cool completely before cutting otherwise they will fall apart. Let chill on the counter for about 30-60 minutes, then place in the fridge until completely cooled, about 1-2 hours.
Scroll down to the recipe card for full instructions.
Strawberry rhubarb bars.
Turn these bars into strawberry rhubarb bars by swapping 1 cup of rhubarb for 1 cup of sliced strawberries!
Tips & tricks.
- To make the bars more tart. If you prefer a more tart rhubarb filling, increase the amount of rhubarb to 3 or 3 ½ cups or decrease the sugar to ¾ cup.
- Add strawberries. Mix things up by swapping 1 cup of rhubarb with 1 cup of sliced strawberries.
- Using frozen rhubarb. Frozen rhubarb contains quite a bit of liquid, so be sure to thaw and drain it first.
- Par-bake the crust. Par-baking the shortbread crust for just 10 minutes allows it to hold up to the rhubarb custard filling, so don't skip this step.
- Double the recipe for a 9x13-inch baking dish. Making bars for a crowd? Just double the recipe and use a 9x13-inch baking dish. The cook time will stay relatively the same. Bake the bars until the center is set and no longer jiggly.
- Make it look pretty. After you sprinkle the streusel crumble over the bars, you can also sprinkle on some slices of rhubarb that will bake into the streusel making the bars look extra pretty! Totally optional.
Frequently asked questions
What fruit is good with rhubarb?
Strawberries are great with rhubarb. If desired, you can swap half the rhubarb for sliced strawberries.
Can I make the bars in a 9x13-inch baking dish?
Yes! Double the recipe and use a 9x13-inch baking dish.
Can I use frozen rhubarb?
When making rhubarb bars, you can swap fresh rhubarb for frozen, but first thaw and drain the frozen rhubarb before using.
How to freeze rhubarb?
Freezing rhubarb is a great way to persevere it for future baking! Simply wash the rhubarb, dice it up, and freeze in freezer bags.
Rhubarb bars can be made 1-2 days in advance and stored in the refrigerator.
Storing rhubarb bars
Cover and store in the refrigerator for up to 4-5 days.
Freezing rhubarb bars
Let cool completely, slice into squares then store in an airtight container in the freezer for up to 3-4 months. Thaw in the refrigerator.
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Rhubarb Shortbread Crumble Bars
- 1 ¼ cups all-purpose flour
- ⅓ cup powdered sugar
- ⅛ teaspoon salt
- 6 tablespoons salted butter, melted
Rhubarb custard filling
- 1 cup granulated sugar
- ¼ cup all-purpose flour
- ⅛ teaspoon salt
- 2 eggs
- ¼ cup heavy whipping cream
- 2 ½ cups rhubarb, chopped
- 1 teaspoon vanilla extract
- ¼ cup all-purpose flour
- ¼ cup old fashioned oats
- ¼ cup brown sugar, packed
- ¼ teaspoon baking powder
- ¼ teaspoon cinnamon
- ¼ cup cold salted butter, cubed
- Heat oven to 350°F and line an 8x8 inch baking dish with parchment paper.
- Whisk together the flour, powdered sugar, and salt. Pour in the melted butter and mix until combined. Sprinkle the dough into your lined baking dish and press down into an even layer. Bake for about 10-12 minutes or until a light golden color.
- While the crust bakes, make the filling. In a large bowl, whisk together the sugar, flour, and salt. Add in the eggs and heavy whipping cream, then whisk until combined. Stir in the rhubarb and pour over the crust. Bake for 20 minutes.
- Meanwhile, make the crumble topping. In a small bowl, whisk together the flour, oats, and brown sugar. Add the cold butter and use a pastry blender to work the butter into the mixture until combined but crumbly. Remove the bars from the oven and sprinkle the crumble over the rhubarb filling. If desired, top with some extra slices of rhubarb.
- Continue to bake for another 25-30 minutes until the filling is set and no longer jiggly.
- Let cool for 30-60 minutes then cover and refrigerate to cool completely before slicing into bars.