Oatmeal Rhubarb Bars

These Oatmeal Rhubarb Bars are like a portable version of fruit crisp! Buttery, sweet, and tangy, these are a family favorite in spring and summer!

The Perfect Summer Dessert

Spatula holding a rhubarb bar above a dish.

In our kitchen, spring = rhubarb. All the rhubarb. I just can’t get enough! 

Today I’m sharing a classic summer dessert. These Oatmeal Rhubarb Bars are wonderful straight from the oven, all warm and gooey. Put it in a bowl with a scoop of ice cream, and you’ve got yourself a divine little crisp. 

But you can also let them cool and have a perfectly portable picnic or lunchbox treat. I served them at room temp for a garage sale, and they were a huge hit. Whatever way you slice it (or scoop it) your family will love these rhubarb crumble bars!

Here’s what makes these Rhubarb Bars SO GOOD:

  • They’re so buttery crisp. Oats and chopped nuts give these bars just the right amount of crunch. I use pecans, but you can use walnuts, mixed nuts, or whatever kind of nut you prefer.
  • They’re packed with flavor. There’s a good sprinkling of ginger in the rhubarb filling (ginger + rhubarb sets my heart a pitter patter) and a hefty sprinkle of cinnamon in the crumble. I heart cinnamon.
  • They’re make ahead and freezer friendly. Bring these bars to your summer BBQs, or hoard them in your freezer for whenever the next craving strikes. I won’t judge.

Rhubarb bars lined up in a row, with a spatula under one piece.

Key Ingredients for Old Fashioned Rhubarb Bars

  • Rhubarb. I know, I know. Duh. But this dessert is proof that rhubarb doesn’t need strawberry. It’s a strong fruit that can stand on its own two…ummm…stalks. And if you have extra rhubarb left over, why not go ahead and make my Rhubarb Custard Cake or Rhubarb Upside Down Cake?
  • Nuts and oats. The crumbly texture of the nuts and oats is what we all want in one of those big, delectable bakery bars, and this one has got it in spades.
  • Butter. It’s important. Full stop.
  • Cinnamon and ginger. These Rhubarb Bars have a hint of cinnamon in the crust, and a sprinkling of ginger in the filling. It brings all the flavors together in a lovely way. 
  • Baking staples. You’ll need all the typical baking ingredients for this recipe: flour, brown sugar, salt, baking soda, sugar, cornstarch, and vanilla. 

How to Make Our Rhubarb Oatmeal Bars

  1. Make the filling. In a medium saucepan, stir together the rhubarb, sugar, cornstarch, water, and ginger. Bring the mixture to a boil, stirring often and making sure the sugar melts and cornstarch is incorporated. Lower the heat to a very gentle simmer and continue to cook until rhubarb is soft and broken down, 7-10 minutes. Add a squeeze of lemon juice. Set aside to cool. I sometimes pop it in the fridge while I’m making the crust.

  1. Make the crust. In a bowl, stir together the pecans, flour, oats, sugar, salt, soda, and cinnamon until well combined. Add the melted butter and the egg, stirring until a crumbly dough begins to form.

  1. Layer. Spread half of the crumb mixture over the bottom of the pan, pressing it down with your hands. Gently spread the rhubarb filling on top. Top with the butter mixture, using your hands to break it up into small crumbles.
  2. Bake. Place the pan in the oven and bake for 30-35 minutes, or until top is golden brown.

Tips & FAQs

Storage

Bars will keep at room temperature, covered, for about 3-4 days. Store in the fridge for easier slicing. They’ll keep 5-7 days.

To re-crisp bars, place them in the oven at 350 degrees for 15 minutes.

Bars can be frozen for up to 3 months. Freeze bars in a single layer (or double layered with parchment paper in between), double wrapped in saran wrap and stored in a freezer safe bag or air tight container.

Slice of oatmeal rhubarb bar on a spatula.

Serving Suggestions

These bars can be served cold, warm, or at room temperature. For a real treat, warm up a bar in the microwave and top with ice cream.

Should you soak rhubarb before baking Rhubarb Bars?

No, the rhubarb doesn’t need to be soaked before baking.

Should rhubarb bars be refrigerated?

You can definitely refrigerate them if you’d like, but they will also keep fine at room temperature for 5 days. They will keep in the fridge for about a week.

How do you prepare rhubarb to eat?

If you’re using rhubarb from your garden, make sure to slice it off close to the ground, and slice off the leaves (they’re poisonous!). Rhubarb should be thoroughly rinsed under cold water, then it’s ready to be chopped and enjoyed in whatever recipe you’re cooking up today!

One slice of rhubarb bar on a spatula.

More Rhubarb Recipes

Combining rhubarb and strawberry is very popular, and I’ve definitely jumped on the bandwagon. 

Here are some rhubarb strawberry recipes, which are all perfect for the summer: Strawberry Rhubarb Fool, Strawberry Rhubarb Ice Cream Floats, and Grilled Angel Food Cake with Strawberry Rhubarb Compote.

More Dessert Bars to Enjoy

Potlucks, reunions, cookouts, picnics…I’ve got desserts for whatever summer throws at you. Here are three of my favorite warm weather desserts: Raspberry Bars, Peach Cobbler Cheesecake Bars, and Lemon Raspberry Bars.

Up close photo highlighting the buttery crumble on top of a rhubarb bar.
Slice of oatmeal rhubarb bar on a spatula.

Oatmeal Rhubarb Bars

Yield: 16
Prep Time: 10 minutes
Cook Time: 35 minutes
Total Time: 45 minutes

These Oatmeal Rhubarb Bars feature a tangy sweet rhubarb filling and buttery crumble topping. They're easy to transport and perfect for summer potlucks and gatherings.

Ingredients

For the crust and crumbles:

  • 2 cups all purpose flour, spooned and leveled
  • 1 1/2 cups old fashioned rolled oats
  • 1 cup packed brown sugar
  • 1 cup chopped pecans
  • 1 teaspoon ground cinnamon
  • 3/4 teaspoon Kosher salt
  • 3/4 teaspoon baking soda
  • 1 cup unsalted butter, melted and cooled
  • 1 large egg, beaten

For the rhubarb filling:

  • 3 cups chopped rhubarb (from about 5-6 large stalks)
  • 1 cup granulated sugar
  • 2 Tablespoons cornstarch
  • 1/4 cup water
  • 1/2 teaspoon ground ginger
  • Squeeze of lemon juice

Instructions

  1. Preheat the oven to 350 degrees. Grease a 9 x 13 inch pan.
  2. Make the filling. In a medium saucepan, stir together the rhubarb, sugar, cornstarch, water, and ginger. Bring the mixture to a boil, stirring often and making sure the sugar melts and cornstarch is incorporated. Lower the heat to a very gentle simmer and continue to cook until rhubarb is soft and broken down, 7-10 minutes. Stir in a squeeze of lemon juice. Set aside to cool. I sometimes pop it in the fridge while I’m making the crust.
  3. Make the crust. In a bowl, stir together the pecans, flour, oats, sugar, salt, soda, and cinnamon until well combined. Add the melted butter and the egg, stirring until a crumbly dough begins to form.
  4. Layer. Spread half of the crumb mixture over the bottom of the pan, pressing it down with your hands. Gently spread the rhubarb filling on top. Top with the butter mixture, using your hands to break it up into small crumbles.
  5. Bake. Place the pan in the oven and bake for 30-35 minutes, or until top is golden brown.

Notes

These bars keep well at room temperature about 3 days or 5-7 days in the fridge. See the above post for freezer instructions.

Recommended Products

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Nutrition Information:
Yield: 16 Serving Size: 1
Amount Per Serving: Calories: 340Total Fat: 17gSaturated Fat: 8gTrans Fat: 0gUnsaturated Fat: 9gCholesterol: 42mgSodium: 129mgCarbohydrates: 44gFiber: 2gSugar: 24gProtein: 4g

Please note nutritional information for my recipes is calculated by a third party service and provided as a courtesy to my readers. For the most accurate calculation, I always recommend running the numbers yourself with the specific products you use.

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