Rhubarb Oatmeal Bars

Rhubarb Oatmeal Bars are a sweet, tangy, and buttery treat that layers tart rhubarb compote between a soft, chewy oatmeal crust and crumbly topping. I love how these bars combine the heartiness of oats with the brightness of rhubarb, making them perfect for breakfast, snacking, or dessert. They’re easy to make, bake beautifully, and slice into clean, satisfying squares.

Why You’ll Love This Recipe

I love how these bars give me the feeling of both a fruit crisp and a hearty snack bar in one bite. The rhubarb adds that punch of tartness I crave, and the oat mixture brings a comforting texture and a touch of nuttiness. They’re not overly sweet, making them feel wholesome and totally justifiable for a morning treat or an afternoon pick-me-up.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

For the rhubarb filling:

• fresh or frozen rhubarb (chopped)

• granulated sugar

• cornstarch

• lemon juice

• vanilla extract

For the oatmeal crust and topping:

• old-fashioned oats

• all-purpose flour

• brown sugar

• baking soda

• salt

• unsalted butter (melted)

Directions

1. I preheat the oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper or grease it lightly.

2. For the filling, I cook the rhubarb, sugar, lemon juice, and cornstarch in a saucepan over medium heat, stirring occasionally, until the rhubarb softens and the mixture thickens—about 10 minutes. I stir in the vanilla and set it aside to cool slightly.

3. In a large bowl, I mix the oats, flour, brown sugar, baking soda, and salt. I pour in the melted butter and stir until the mixture is crumbly and evenly moistened.

4. I press about two-thirds of the oat mixture into the bottom of the prepared pan to form a crust.

5. I spread the rhubarb filling evenly over the crust.

6. I sprinkle the remaining oat mixture over the top and press it down gently.

7. I bake for 30–35 minutes, or until the top is golden and the filling is bubbling at the edges.

8. I let the bars cool completely in the pan before slicing—this helps them set and cut cleanly.

Servings and timing

This recipe makes about 9–12 bars. It takes 15–20 minutes to prep, 30–35 minutes to bake, and at least 1 hour to cool and set. I usually plan for about 1½ to 2 hours total.

Variations

Sometimes I mix chopped strawberries with the rhubarb for a sweeter flavor, or add a sprinkle of cinnamon to the oat mixture for warmth. I’ve also added chopped walnuts or almonds to the topping for a nutty crunch. For a dairy-free version, I use coconut oil instead of butter.

storage/reheating

I store the bars in an airtight container at room temperature for up to 2 days, or in the fridge for up to 5 days. To reheat, I warm them in the microwave for 10–15 seconds or enjoy them cold for a firmer texture. They also freeze well—just wrap each bar individually and thaw when needed.

FAQs

Can I use frozen rhubarb?

Yes, I use it straight from the freezer—just add an extra minute or two to the cooking time for the filling and drain off excess liquid if needed.

How do I keep the bars from falling apart?

Letting them cool completely before slicing is key. I sometimes chill them in the fridge for cleaner cuts.

Can I double the recipe?

Absolutely. I double the ingredients and bake in a 9×13-inch pan, adding a few extra minutes to the bake time.

Can I use quick oats instead of old-fashioned oats?

Yes, but the texture will be a little softer. I prefer old-fashioned oats for a chewier bite.

What’s the best way to cut them cleanly?

I use a sharp knife and wipe it between cuts. Cooling the bars completely makes a big difference.

Conclusion

Rhubarb Oatmeal Bars are one of my favorite ways to bake with rhubarb—easy, satisfying, and full of that tangy-sweet flavor I love. Whether I pack them for a picnic, slice them up for brunch, or enjoy one with coffee, these bars are a go-to treat I always feel good about making and sharing.