Rhubarb Oatmeal Bars

For a taste of spring, these moist and chewy rhubarb oatmeal bars are filled with tart rhubarb and sweet strawberry jam. They’re as good as rhubarb pie but so much easier to make!

Looking for more rhubarb recipes? You’ll love this rhubarb layer cake with candied rhubarb curls, homemade rhubarb cordial, and roasted rhubarb ice cream.

Updated: I originally developed this recipe in 2013, but have updated the post in 2021.

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Why You’ll Love This Recipe

Easy to Make. What I love about a crumb bar recipe is how easy they are to make. Since you only need to make one mixture for both the bottom crust and the crumb topping, these bars come together quickly.

So Perfect in the Spring. I look forward to fresh rhubarb from our garden every spring, and these bars are always one of the first recipes I make.

Simple Pantry Ingredients. You’ll just need basic staples to make this recipe, and you probably have everything on hand already.

High Altitude Tested. I develop all the recipes on my site for Denver’s altitude of 5,280 feet. If you’re at a lower or higher elevation, please see my FAQs for guidance on adjusting recipes for your altitude.

TIP: Either fresh or frozen rhubarb works equally well in these rhubarb oatmeal bars. You can find fresh rhubarb in grocery stores in early spring (from April-June), or check the freezer section of your local farmer’s market for frozen rhubarb.

Ingredients

Crust and Topping

• All-Purpose Flour. Provides structure and strength to the crust and topping.
• Old-Fashioned Oats. Adds crunch and texture.
• Dark Brown Sugar. Adds sweetness and a hint of molasses.
• Coarse Kosher Salt. Balances the sweetness.
• Baking Powder. Provides a little leavening.
• Cinnamon. Nicely complements the flavor of the rhubarb.
• Unsalted Butter. Adds richness and moisture to bind the crust together.

Filling

• Rhubarb. You can use either fresh, or frozen rhubarb, whichever you can easily find.
• Baking Soda. Neutralizes the bitterness in the rhubarb.
• Granulated Sugar. Adds sweetness and moisture.
• All-Purpose Flour. Helps to thicken the juices of the filling.
• Strawberry Jam. Strawberries are very complementary to rhubarb, and the jam adds more thickness and sweetness.
• Lemon Juice. A touch of lemon helps to balance the sugar and enhances the flavor of the rhubarb and strawberries.
• Vanilla Extract. Flavor.

TIP: If you grow your own rhubarb, you can easily freeze it to bake with later. First, remove and discard the toxic leaves. Wash the stalks well, and let them dry. Chop the stalks into 1/2 inch pieces, and freeze in zip top freezer bags, pressing out as much air as possible.

Instructions

Make the Oatmeal Crust & Topping Mixture.

• Preheat the oven to 350.  Spray a square 8×8 baking dish with non-stick spray.
• In your food processor, or with a pastry cutter, combine the crust/topping ingredients until pea-sized pieces of butter remain.
• Reserve 1 ½ cups of the crumbs for the topping (chill in the refrigerator until needed), and press the remainder of the crumbs firmly against the bottom of the baking dish.  Bake crust for 20 minutes.

Combine the Rhubarb Filling.

• Meanwhile, in a bowl toss the rhubarb with the baking soda, sugar and flour until all the fruit is coated.  Stir in the jam, lemon juice and vanilla.

Bake the Rhubarb Filling.

• After the crust has baked for 20 minutes, remove from the oven.
• Spread the rhubarb mixture over the hot crust.  Bake for 30 minutes.

Add the Topping and Finish Baking.

• Sprinkle the reserved crumbs over the fruit and bake for an additional 20-25 minutes until topping is golden brown.
• Let cool on the counter for at least two hours to set before slicing into squares.

Be sure to read all of my BAKING FAQs where I discuss ingredients, substitutions and common baking questions, so that you can be successful in your own baking!

Frequently Asked Questions

What kind of oats do you use in the crust and topping?

I use old-fashioned oats. They have a better texture than instant oats, and cook much more quickly than steel-cut oats, so they’re my go-to oats for cooking and baking.

Should I use fresh or frozen rhubarb?

You can use either, whichever is easiest to find. Depending on where you live, you might only be able to buy fresh rhubarb in early spring (from April-June) in your grocery store. My local grocery store (Kroger) almost never stocks frozen rhubarb, although I’ve been able to find it at Sprouts.

Can I make these bars ahead of time and freeze them?

I haven’t tried freezing these bars, but since the filling is so moist, I’m guessing it would make the crust and topping soggy during the thawing process.

Can I make these bars gluten-free?

Yes, you can easily make gluten free rhubarb oatmeal bars by using your favorite measure-for-measure gluten free flour in place of the all-purpose flour.

What if I want to add fresh strawberries instead of the strawberry jam?

If you do, you’ll need to reduce the strawberries quite a bit first, so they’re not too juicy. I have a recipe for brown butter strawberry crumb bars, which are just fantastic.

How should I store leftover rhubarb bars?

You should refrigerate the bars, in an airtight container, for up to 2 days. The filling is so moist that after 2 days, the crust will start to get a little soft.

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