If you’ve got rhubarb on your hands and no idea what to do with it, you need to try these Easy Rhubarb Oat Bars. They’re sweet, tart, buttery, crumbly, and everything you could want in a dessert-slash-breakfast-bar situation. I bake these every spring when rhubarb is overflowing at the farmer’s market or popping up in my garden like it owns the place. They’re perfect with your morning coffee or as a light dessert with a dollop of whipped cream. Bonus: they make your whole house smell like a cozy country kitchen.
These bars are seriously low effort, high reward — no mixer, no fuss. If you can stir and layer, you can bake these. They’ve got a buttery oat crumble base that doubles as the topping (yay for fewer dishes), and the rhubarb filling is naturally tangy with just the right hint of sweetness. Let’s get into it!
Ingredients
For the Oat Crust & Topping:
- 1 cup all-purpose flour
- 1 cup old-fashioned rolled oats
- ¾ cup brown sugar, packed
- ½ teaspoon salt
- ½ teaspoon baking soda
- ½ cup (1 stick) unsalted butter, melted
- 1 teaspoon vanilla extract
For the Rhubarb Filling:
- 2 ½ cups fresh rhubarb, chopped
- ⅓ cup granulated sugar
- 1 tablespoon cornstarch
- 1 tablespoon lemon juice
- ½ teaspoon cinnamon (optional but delightful)
Serving Size
Makes 12 bars (or 9 big ones if you cut generously!)
Time Breakdown
Prep Time: 10 minutes
Cook Time: 35 minutes
Total Time: 45 minutes
Instructions
- Preheat your oven to 350°F (175°C) and line an 8×8-inch baking dish with parchment paper. You can also lightly grease it if you’re not using parchment.
- Mix the crust and topping. In a large bowl, combine flour, oats, brown sugar, salt, and baking soda. Pour in melted butter and vanilla. Stir until everything’s evenly moistened and crumbly.
- Set aside about ¾ cup of the oat mixture for the topping. Press the rest into the bottom of your prepared pan to form the crust.
- Make the rhubarb filling. In a medium saucepan over medium heat, combine rhubarb, sugar, lemon juice, and cornstarch. Stir frequently and cook for about 5–6 minutes, until the mixture becomes thick and bubbly. If using cinnamon, stir it in now.
- Assemble. Pour the rhubarb filling evenly over the crust. Sprinkle the reserved oat mixture on top — don’t worry if it looks rustic!
- Bake for 30–35 minutes, or until the topping is golden brown and the filling is bubbling at the edges. Let cool completely in the pan before cutting into bars. Trust me — they hold together way better once cooled.
How to Serve
Serve these chilled straight from the fridge for a firmer bite, or warm them up for a gooey, cozy treat. Add whipped cream or a scoop of vanilla ice cream if you’re feeling extra.
Storing Tips
Keep leftovers in an airtight container in the fridge for up to 5 days. They also freeze great — just wrap them tightly and store for up to 2 months.
Related Post: Easy One Bowl Chocolate Cake Recipe
Final Thoughts
These rhubarb oat bars are everything I love about spring baking — easy, rustic, and bursting with flavor. They’re a no-fail treat that even baking beginners can pull off with confidence. Whether you’re trying to use up garden rhubarb or just want something sweet without the sugar overload, these bars check all the boxes.
Let me know in the comments if you try them — I’d love to hear how they turned out (and if your kids or coworkers devoured them like mine do!).