Rhubarb Oatmeal Bars
These Rhubarb Oatmeal Bars are a perfect balance of tart rhubarb, sweet oats, and buttery crumb topping. Easy to make and packed with flavor, they’re a wholesome treat for breakfast, snacks, or dessert.
Sweet and Tart Rhubarb Bars
Growing up, we had a giant rhubarb patch that seemed to take over a corner of the backyard every spring. The minute those ruby-red stalks started popping up, we knew Mom’s rhubarb season had officially begun.
Mom could turn rhubarb into anything. Pies, jams, crisps, cakes — you name it, she made it. Now, whenever I bake with rhubarb, it’s like a little throwback to those sunny backyard days and Mom’s endless creativity with that magical plant that just kept growing.
For more rhubarb recipes, try our Rhubarb Bread Recipe and Strawberry Rhubarb Streusel Muffins.
Why This Recipe Works:
- Perfect balance of sweet and tart – the rhubarb gives a bright pop of flavor that pairs beautifully with the buttery oat crust.
- Simple – they’re easy to make with simple ingredients, yet look and taste like something from a bakery.
- Versatile – perfect for breakfast, dessert, or an afternoon snack.
- Freeze well – so you can enjoy a taste of rhubarb season long after it’s gone.
What You’ll Need:
- rhubarb
- granulated sugar
- lemon juice
- cornstarch
- oatmeal
- all-purpose flour
- brown sugar
- baking soda
- kosher salt
- ground cinnamon
- unsalted butter
- vanilla extract
Instead of using rhubarb, you can use jam like we do in our Oatmeal Raspberry Jam Bars.
How to make Rhubarb Oatmeal Bars:
Step 1
Prep rhubarb. Discard leaves and both ends of rhubarb. Then cut in thin slices.
Step 2
Cook rhubarb mixture. Combine 4 cups of sliced rhubarb, granulated sugar, and fresh lemon juice in medium saucepan. Cook on medium for 6-7 minutes or until rhubarb is broken down, using a wooden spoon to stir frequently. Combine one tablespoon of cornstarch with one tablespoon of water in a small bowl – and add to pan to thicken. Simmer for another minute and then remove from heat.
You can add rhubarb mixture to a blender and puree until smooth or keep mixture chunky (although the rhubarb will be broken down).
Step 3
Make oatmeal crumble. In a mixing bowl, combine oatmeal, flour, brown sugar, baking soda, kosher salt, and ground cinnamon. Stir to combine.
Then add melted butter and vanilla and stir well.
Step 4
Assemble bars.
- Preheat oven to 350-degrees F. Add a piece of parchment paper to a 9×13 inch pan.
- Reserve about 1 cup of the oatmeal crumble and then press remaining mixture into the pan, distributing evenly to all sides.
- Spread the rhubarb mixture over the oatmeal layer, smoothing evenly. Add the additional one cup of reserved sliced rhubarb over the cooked rhubarb layer.
- Use your hands to sprinkle the remaining one cup of oatmeal crumble over the rhubarb layer.
Step 5
Bake rhubarb crumble bars. Bake rhubarb bars in preheated oven for about 30 minutes, or until bars are set.
Step 6
Cool bars. Let the rhubarbs set in pan for about 30 minutes. Then carefully remove using parchment paper as handles. Set bars on a wire cooling rack.
Step 7
Slice. Slice rhubarb oatmeal bars into 12 equal-sized squares.
How to store rhubarb bars:
- Once your rhubarb oatmeal bars have cooled completely, cut them into squares and store them in an airtight container. They’ll stay fresh at room temperature for about 2 days, or you can keep them in the refrigerator for up to a week. If you like them a little firmer and chilled, the fridge is definitely the way to go!
- To freeze, place the cooled bars in a single layer on a baking sheet and freeze until solid (about an hour). Then transfer them to a freezer-safe container or ziplock bag, separating layers with parchment paper to prevent sticking. They’ll keep well for up to 3 months.
How to freeze rhubarb (just the plant)
- You can freeze the actual rhubarb too! Start by washing and trimming the stalks — remove any leaves (they’re toxic) and cut off the ends. Then slice the rhubarb into 1-inch pieces or whatever size you typically use for baking.
- Blot dry with a paper towel to remove excess moisture. Spread the pieces out on a baking sheet lined with parchment paper and freeze until solid, about 1–2 hours. This step keeps the pieces from clumping together.
- Once frozen, transfer the rhubarb to a freezer-safe bag or airtight container, label it with the date, and store it for up to a year. When you’re ready to use it, you can usually add it straight to your recipe frozen – no need to thaw unless your recipe specifically says otherwise!
Other Delicious Bar Recipes:
Looking for other delicious bar recipes? Look no further.
Kitchen Tools Used: (affiliate links)
xoxo ~Sue
Rhubarb Oatmeal Bars
Ingredients
For the rhubarb filling:
- 5 cups rhubarb (about one pound) – sliced
- 1/2 cup granulated sugar (100 grams)
- 1 Tablespoon freshly squeezed lemon juice
- 2 Tablespoons cornstarch
For the oatmeal mixture:
- 1 ¾ cups all-purpose flour (210 grams)
- 1 ¾ cups old fashioned oatmeal (140 grams)
- 2/3 cup brown sugar (145 grams)
- 1 ¼ teaspoon baking soda
- 1 teaspoon ground cinnamon
- 1 teaspoon kosher salt
- 1 Tablespoon vanilla extract
- 13 Tablespoons unsalted butter – melted
Instructions
- Prep rhubarb. Discard leaves and both ends of rhubarb. Then cut in thin slices.
- Cook rhubarb mixture. Combine 4 cups of sliced rhubarb, granulated sugar, and fresh lemon juice in medium saucepan. Cook on medium for 6-7 minutes, using a wooden spoon to stir frequently. Combine two tablespoons of cornstarch with two tablespoons of water and add to pan to thicken. Simmer for another minute and then remove from heat.You can add rhubarb mixture to a blender and puree until smooth or keep mixture chunky (although the rhubarb will be broken down).5 cups rhubarb (about one pound), 1/2 cup granulated sugar (100 grams), 1 Tablespoon freshly squeezed lemon juice, 2 Tablespoons cornstarch
- Make oatmeal crumble. In a mixing bowl, combine oatmeal, flour, brown sugar, baking soda, kosher salt, and ground cinnamon. Stir to combine.Then add melted butter and vanilla and stir well.1 ¾ cups all-purpose flour (210 grams), 1 ¾ cups old fashioned oatmeal (140 grams), 2/3 cup brown sugar (145 grams), 1 ¼ teaspoon baking soda, 1 teaspoon ground cinnamon, 1 teaspoon kosher salt, 13 Tablespoons unsalted butter, 1 Tablespoon vanilla extract
- Assemble bars.– Preheat oven to 350-degrees F. Add a piece of parchment paper to a 9×13 inch pan.– Reserve about 1 cup of the oatmeal crumble and then press remaining mixture into the pan, distributing evenly to all sides.– Spread the rhubarb mixture over the oatmeal layer, smoothing evenly. Add the additional one cup of reserved sliced rhubarb over the cooked rhubarb layer.– Use your hands to sprinkle the remaining one cup of oatmeal crumble over the rhubarb layer.
- Bake rhubarb crumble bars. Bake rhubarb bars in preheated oven for about 30 minutes, or until bars are set.
- Cool bars. Let the rhubarbs set in pan for about 30 minutes. Then carefully remove using parchment paper as handles. Set bars on a wire cooling rack.
- Slice. Slice rhubarb oatmeal bars into 12 equal-sized squares.
Notes
- Once your rhubarb oatmeal bars have cooled completely, cut them into squares and store them in an airtight container. They’ll stay fresh at room temperature for about 2 days, or you can keep them in the refrigerator for up to a week. If you like them a little firmer and chilled, the fridge is definitely the way to go!
- To freeze, place the cooled bars in a single layer on a baking sheet and freeze until solid (about an hour). Then transfer them to a freezer-safe container or ziplock bag, separating layers with parchment paper to prevent sticking. They’ll keep well for up to 3 months.
Tart, sweet, and crumbly – utterly delicious!
To die for!