There’s something nostalgic about oat bars—especially when they’re layered with tangy rhubarb and a buttery crumble top.

These Rhubarb Oatmeal Bars bring together the earthy texture of oats, the richness of brown sugar, and the bright, zingy burst of rhubarb for a treat that’s as comforting as it is refreshing.

Why I Love This Recipe

It’s the perfect mix of sweet and tart—balanced and vibrant in every bite.

The crumbly oat base and topping make it feel hearty, like a rustic dessert or a cheeky breakfast.

It’s quick to assemble, no mixer required, and ideal for using up extra rhubarb.

Every square tastes like early summer, warm sunshine, and something Grandma might’ve made.

What You’ll Need (Ingredient Highlights)

Rolled oats – Old-fashioned oats add the perfect chewy-crisp texture.

Brown sugar – Dark brown adds deep, caramel-like sweetness.

Rhubarb – Bright, tart, and juicy; can be fresh or frozen.

All-purpose flour – Gives structure to the crumb layers.

Butter – Melted to bind everything into rich, golden crumbs.

Cinnamon – Adds warmth that enhances both oat and rhubarb flavors.

Baking powder & salt – For lightness and balance.

Water (optional) – Helps soften fresh rhubarb if needed.

Pro Tips Before You Start

Use parchment paper – Makes removing the bars and cleanup easier.

Melted butter = better mixing – Helps bind dry ingredients without fuss.

Fresh rhubarb tip – Toss with a little water so it doesn’t dry out during baking.

Press the base firmly – This helps it hold together after baking.

Cool completely before slicing – It sets as it cools, making clean cuts easier.

How to Make Rhubarb Oatmeal Bars

Step 1: Preheat and Prepare

Preheat oven to 350°F (175°C).

Grease a 9×13-inch baking pan or line it with parchment.

Step 2: Mix the Dry Ingredients

In a large bowl, combine oats, flour, brown sugar, baking powder, cinnamon, and salt. Mix well.

Step 3: Add Butter

Pour in melted butter and mix until the texture resembles damp sand—crumbly but holds together when pressed.

Step 4: Create the Bottom Layer

Press about two-thirds of the crumb mixture into the bottom of the pan, spreading into an even layer.

Step 5: Add the Rhubarb

If using fresh rhubarb, toss it with water to help it soften while baking.

Evenly scatter the rhubarb across the base.

Step 6: Top with Remaining Crumbs

Sprinkle the remaining crumb mixture over the rhubarb, ensuring even coverage.

Step 7: Bake

Bake for 30–35 minutes until the top is golden brown and the rhubarb is tender.

Step 8: Cool and Slice

Let the bars cool completely in the pan before cutting into squares.

What to Serve It With

Vanilla ice cream – Melts into the warm crumble for the ultimate bite.

Greek yogurt – Makes it feel like a fancy breakfast.

Drizzle of honey – Adds floral sweetness to the tart fruit.

Afternoon tea or coffee – A cozy pairing.

Fresh mint or whipped cream – For garnish and flair.

Variations / Substitutions

Swap the fruit – Strawberries, raspberries, or apples pair well with rhubarb.

Add nuts – Chopped walnuts or pecans add crunch and warmth.

Make it gluten-free – Use GF oats and a gluten-free flour blend.

Add citrus zest – Lemon or orange zest brightens everything.

Less sugar – Reduce sugar slightly if you prefer a more tart bar.

Storage & Leftovers

Room temperature: Store in an airtight container for 2–3 days.

Fridge: Keep up to 5 days for firmer bars.

Freeze: Wrap bars individually and freeze up to 2 months.

Thawing: Let thaw at room temperature or warm slightly in the oven.

Best eaten within 2 days – That’s when the texture is just right.

FAQs

Can I use frozen rhubarb?
Yes! Just thaw and drain it well before using.

Can I add other fruits?
Absolutely. Strawberries or raspberries make great partners with rhubarb.

Do I need to peel the rhubarb?
Nope! Just chop and use—it softens beautifully when baked.

Is it too tart for kids?
Not at all. The brown sugar and buttery crumbs balance the tang.

Can I make this ahead of time?
Yes, and it actually cuts better once fully cooled or chilled.

Can I skip the cinnamon?
Sure—but it adds warmth and depth to the flavor.

How do I reheat leftovers?
A quick warm-up in the toaster oven makes them taste fresh-baked again.

Final Thoughts

These Rhubarb Oatmeal Bars are the kind of rustic dessert that feels homemade in the best way.

With simple ingredients and an irresistibly chewy texture, they bring together tart rhubarb and buttery oats for a treat that’s great any time of day.

Make a batch and share—or don’t. They go fast either way.

The Boat Shed Kitchen