These Rhubarb Oat Bars are a delightful blend of tart rhubarb and sweet, buttery oat crumble. With a chewy base and a golden crumb topping, they make the perfect springtime treat or a year-round snack when you have frozen rhubarb on hand. Perfect for breakfast, dessert, or an afternoon coffee break, these bars are simple to make and bursting with flavor.

Why You’ll Love This Recipe

A perfect way to use fresh or frozen rhubarb
Buttery oat crumble gives texture and sweetness
Easy to make with simple pantry ingredients
Great for meal prepping and storing
Versatile — serve as a dessert or snack
Can be made gluten-free with simple swaps
Balanced flavor: tart rhubarb meets sweet crumble
Freezes well for longer storage
Family-friendly and crowd-pleasing
No mixer required

ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Rhubarb (fresh or frozen)
Granulated sugar
Cornstarch
All-purpose flour
Old-fashioned rolled oats
Brown sugar
Baking soda
Salt
Ground cinnamon (optional)
Unsalted butter (melted)
Vanilla extract

directions

Preheat your oven to 350°F (175°C). Grease or line an 8×8-inch baking pan with parchment paper.
In a bowl, toss the chopped rhubarb with sugar and cornstarch. Set aside to let the juices release.
In a separate bowl, combine flour, oats, brown sugar, baking soda, salt, and cinnamon. Stir in melted butter and vanilla until crumbly.
Press about two-thirds of the oat mixture into the prepared baking pan to form the crust.
Spread the rhubarb mixture evenly over the crust.
Sprinkle the remaining oat mixture over the top.
Bake for 35–40 minutes or until the top is golden and the filling is bubbly.
Let the bars cool completely in the pan before cutting into squares.

Servings and timing

This recipe makes about 12 bars.
Prep time: 15 minutes
Cook time: 35–40 minutes
Total time: Approximately 55 minutes

Variations

Gluten-free: Use a gluten-free flour blend and certified gluten-free oats.
Add fruit: Mix in strawberries or raspberries for a sweeter twist.
Spices: Add ground ginger or nutmeg for extra warmth.
Crumble topping: Add chopped nuts or coconut flakes to the topping for added crunch.
Lemon twist: Add lemon zest to the rhubarb mixture for brightness.

storage/reheating

Store rhubarb oat bars in an airtight container at room temperature for up to 2 days or refrigerate for up to 5 days.
To reheat, warm a bar in the microwave for 10–15 seconds if desired.
For longer storage, freeze the bars (wrapped individually or in layers with parchment paper) for up to 3 months. Thaw in the refrigerator or at room temperature.

FAQs

How do I know when the bars are done baking?

The top should be golden and the rhubarb filling should be bubbling around the edges.

Can I use frozen rhubarb?

Yes, but thaw and drain it first to remove excess liquid.

Can I substitute quick oats for rolled oats?

You can, but the texture will be softer and less chewy.

Is it necessary to peel rhubarb?

Not usually. Only peel if the stalks are very thick or fibrous.

Can I make these bars dairy-free?

Yes, substitute the butter with a vegan butter or coconut oil.

What’s the best way to cut these bars cleanly?

Let them cool completely, then use a sharp knife cleaned between cuts.

Can I use honey or maple syrup instead of sugar?

It’s not recommended as it can alter the texture. Stick with granulated sweeteners for best results.

Can I add a glaze or drizzle?

Yes, a simple vanilla or lemon glaze works well once the bars are cooled.

Are these bars freezer-friendly?

Absolutely. Wrap them well and freeze for up to 3 months.

Do I need to cook the rhubarb before adding it to the bars?

No, it will soften and cook during baking.

Conclusion

Rhubarb Oat Bars are a timeless, easy-to-make treat that balances tart and sweet flavors with a satisfying oat crumble. Whether you’re looking for a seasonal dessert or a make-ahead snack, these bars are a must-try. With simple ingredients and customizable options, you’ll find yourself coming back to this recipe again and again.

Rhubarb Oat Bars