Skip to Content

Rhubarb Oatmeal Bars w/ Vanilla Glaze

Vegetarian

Sweet and tart; these simple rhubarb oatmeal bars drizzled with vanilla glaze are the perfect wholesome treat for dessert or even brunch. Naturally vegetarian.

Rhubarb oatmeal bars with flowers and a bowl of glaze.

Jessica Halverstadt is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. As an Amazon Associate, I earn from qualifying purchases.

What’s to love about this recipe?

  • The versatility! These multipurpose bars can be served hot with ice cream for dessert or cooled. Since they involve fruit and oats they are also suitable for breakfast or brunch. And if you’re like me, you’ll find yourself snacking on them throughout the day too. Which I might add is perfectly acceptable…..and understandable.
  • The ease! Although there are several components to these oatmeal bars, preparing them is really quite simple and only takes about ten minutes.
  • The balance of flavors! When it comes to dessert, I just love the combination of sweet and tart – these rhubarb bars are just that. The addition of warming spices like cinnamon and nutmeg along with the oats and vanilla make them irresistibly wholesome.
Finished rhubarb bars garnished with flowers and a bowl of glaze with a spoon.

Ingredients + notes & substitutions

Ingredients for rhubarb oatmeal bars (see recipe card).
  • Rhubarb: Are you ready to have your mind blown? ……….. Rhubarb is actually a vegetable. Shocking, I know. If like many, you are unfamiliar with rhubarb, it’s a crunchy stalk (similar to celery) commonly used in baked goods like pie and crumbles. Since it’s exceptionally tart mixing it with sugar makes it more palatable. Another important fact pertaining to rhubarb is that the leaves are highly toxic and thus should not be consumed. It is most commonly available April through June here in the states and can be found at most big supermarkets in the produce section.
  • Granulated sugar: Combining the rhubarb with some sugar reduces the tartness. If you prefer your rhubarb on the tart side feel free to reduce the sugar to a tablespoon or two. Sugar also helps draw out moisture from the rhubarb.
  • Cornstarch: To thicken the rhubarb filling. Failing to use cornstarch will result in mushy bars.
  • Lemon juice: Lemon juice aids in the extraction of liquid from the rhubarb as well. I typically use bottled lemon juice for this recipe but if you have a fresh lemon around that you need to use, go for it!
  • All-purpose flour
  • Old fashioned rolled oats: The best choice for baked goods.
  • Brown sugar: Using brown sugar rather than granulated sugar for the bars ensures they are moist and more fully flavored.
  • Ground cinnamon: Cinnamon pairs exceptionally well with rhubarb. I love the sweet and warm notes that it adds.
  • Baking powder: For leavening.
  • Ground nutmeg: Nutmeg is another cozy warming spice that works well with rhubarb.
  • Kosher salt: To bring out the flavors.
  • Unsalted butter: Salted butter will work just as well and shouldn’t alter the flavor profile significantly so if that’s all you got, no sweat!
  • Powdered sugar: The base of the vanilla glaze.
  • Vanilla extract or paste
  • Whole milk: For thinning the glaze.

How do you make these rhubarb oatmeal bars? (+ tips)

  1. Preheat oven to 350 degrees. For easy clean-up, line an 8×8″ baking dish with parchment paper. Leave an extra couple of inches of paper on each side so that you may lift the finished bars out of the pan – this allows you to more easily slice the bars while keeping them intact. If you do not have any parchment paper, liberally spray with non-stick cooking spray. Set the prepared pan aside.
  2. In a medium bowl, combine the rhubarb, sugar, cornstarch, and lemon juice. Set aside.
Diced rhubarb in a bowl.

3. In a medium sized mixing bowl, whisk together the all-purpose flour, old fashioned rolled oats, brown sugar, cinnamon, baking powder, nutmeg, and salt.

Dry ingredients in a bowl.

4. Add the butter and stir to combine.

Oatmeal bar batter in a bowl.

5. Reserve one cup of the oatmeal mixture then transfer the remaining batter to the baking dish. Use your hands to press it down evenly throughout the pan.

6. Scoop the rhubarb mixture atop the crust using a slotted spoon and spread it evenly. You’ll want to avoid transferring any liquid that has been drawn out of the rhubarb. Top with the reserved oatmeal mixture from step five.

Construction of rhubarb oatmeal bars in three stages.

7. Bake for minutes 40-50 minutes until the top is golden brown the fruit begins to bubble.

8. Meanwhile, prepare the vanilla glaze by whisking together the powdered sugar, vanilla, and milk until smooth. Set aside. ** Feel free to pass on the glaze if you’d like.

Vanilla glaze with a spoon in a bowl.

9. Remove from the oven and allow to cool completely before drizzling with glaze and slicing. If preferred, drizzle immediately with glaze, slice, and serve warm with ice cream.

How to store

Refrigerate in an airtight container for up to five days.

Close up of bars with flowers.
Close-up of stack of three oatmeal bars.

More delicious desserts that can be served for breakfast:

  • Blueberry Rhubarb Buckle Cake w/ Cardamom Streusel: Easy, super moist buckle cake with fresh blueberries and rhubarb topped with cardamom and cinnamon streusel; a wonderful choice for brunch or dessert.
  • Pumpkin Cream Cheese Coffee Cake: Sandwiched between two layers of moist pumpkin-infused cake sits a luscious cheesecake-like cream cheese filling. To top that off is a crunchy pumpkin spice streusel. This perfect for fall pumpkin cream cheese coffee cake is ideal for breakfast, brunch, or dessert (or all three!!!).

If you make these rhubarb oatmeal bars I’d love your feedback. Please leave a comment and/or a rating below as I greatly value your opinion. Or snap a pic and tag me on Instagram @taoofspiceblog. Love, light, and happy cooking ya’ll ♥

Rhubarb oatmeal bars with flowers and a bowl of glaze.

Rhubarb Oatmeal Bars w/ Vanilla Glaze

Yield: 9 bars
Prep Time: 10 minutes
Cook Time: 40 minutes
Total Time: 50 minutes

Sweet and tart; these simple rhubarb oatmeal bars drizzled with vanilla glaze are the perfect cozy treat for dessert or even brunch. Naturally vegetarian.

Ingredients

Rhubarb Filling

  •  3 cups rhubarb, diced 1/4-inch thick
  • 3 tablespoons sugar
  • 1 1/2 tablespoons cornstarch
  • 1 tablespoon lemon juice

Oatmeal Bars

  • 1 1/2 cup all-purpose flour
  • 1 1/2 cup old fashioned rolled oats
  • 1 cup brown sugar
  • 1 tablespoon ground cinnamon 
  • 2 teaspoons baking powder 
  • 1 teaspoon ground nutmeg 
  • 1/2 teaspoon salt
  • 1 cup (2 sticks) melted butter 

Vanilla Cream Cheese Glaze (optional)

  • 1/2 cup powdered sugar 
  • 1 teaspoon vanilla extract
  • 1 1/2 tablespoons whole milk 

Instructions

  1. Preheat oven to 350 degrees. Line an 8x8" baking dish with parchment paper or liberally spray with non-stick cooking spray. Set aside.
  2. In a medium bowl, combine the rhubarb, sugar, lemon juice, and cornstarch. Set aside.
  3. In a medium mixing bowl, whisk together the all-purpose flour, old-fashioned rolled oats, brown sugar, cinnamon, baking powder, nutmeg, and salt.
  4. Add the butter and stir to combine.
  5. Reserve one cup of the oatmeal mixture. Transfer the remaining batter to the baking dish and use your hands to press it down evenly.
  6. Scoop the rhubarb mixture atop the crust using a slotted spoon and spread it evenly. You'll want to avoid transferring any liquid that has been drawn out of the rhubarb. Top with the reserved oatmeal mixture from step five.
  7. Bake for minutes 40-50 minutes until the top is golden brown the fruit begins to bubble.
  8. Meanwhile, prepare the vanilla glaze by whisking together the powdered sugar, vanilla, and milk until smooth. Set aside.
  9. Remove from oven and allow to cool completely before drizzling with glaze and slicing. If preferred, drizzle immediately with glaze, slice, and serve warm with ice cream.

Storage: Refrigerate in an airtight container for up to five days.

Did you make this recipe?

Please leave a comment on the blog or share a photo on Instagram

Skip to Recipe