Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars Recipe

There’s something wonderfully nostalgic about biting into a sweet-tart bar that hits the perfect balance between chewy, crumbly, and jammy. Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars are exactly that sort of treat—a comforting, crowd-pleasing classic that’s as simple as it is sensational. This recipe is a true celebration of humble pantry staples and vibrant rhubarb, resulting in a dessert bar you’ll find yourself craving for breakfast, snack time, or a cozy finish to dinner. Let’s get baking and bring this retro favorite back into the spotlight!

Ingredients You’ll Need

The magic of Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars lies in just a handful of ingredients that mingle beautifully together. Each one brings its own character: a bit of chew, a touch of sweetness, that irresistible buttery crumb, and a punch of tart rhubarb color.

• Oatmeal: Both rolled oats and quick oats work here, giving the bars hearty texture and wholesome flavor.
• All-Purpose Flour: Acts as the backbone of the crumb mixture, helping everything hold together for the perfect bite.
• Brown Sugar: Adds sweet, caramelized depth and softness, complementing the tangy rhubarb.
• Salted Butter (melted): Richly flavors and binds the crumble mixture, while the salt enhances every flavor note.
• Rhubarb (sliced in ½-inch pieces): The tart, colorful star that turns gooey and soft after baking, giving these bars their signature zing.

How to Make Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars

Step 1: Preheat Your Oven

Start by heating your oven to 350ºF so it’s ready for your bars. An oven that’s fully preheated ensures your crumble bakes up perfectly golden and your rhubarb softens just right. Take this time to line or grease your 8×8-inch baking pan for easy bar removal later!

Step 2: Mix the Dry Ingredients

In a mixing bowl, combine your oats, flour, and brown sugar. Give them a good stir to evenly distribute the brown sugar and ensure every bite gets that delicious chewy, caramelized flavor. This is the crumble base that brings heart and soul to your Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars.

Step 3: Add the Butter

Pour in the melted salted butter and gently stir the mixture with a fork or spatula. Watch as it transforms from dry and sandy to a soft, cohesive crumble. The butter not only adds rich flavor but binds all the ingredients together, giving the bars their irresistible texture.

Step 4: Press the Crust

Take about two thirds of your oat mixture and firmly press it into the bottom of your prepared pan. Use your hands or the back of a spoon to really pack it down. This forms the sturdy base for your Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars and ensures every bar holds together beautifully after baking.

Step 5: Add the Rhubarb

Scatter your sliced rhubarb evenly over the oat crust. This generous layer is what gives the bars their fruity tartness and those gorgeous pops of pink. Rhubarb will soften and release delightful juices as it bakes, creating a jammy center.

Step 6: Top and Bake

Sprinkle the remaining oat mixture over the rhubarb, making sure there are plenty of crumbly bits for texture. Slide the pan into the center of your oven and bake for about 30 minutes, or until the top is golden and the rhubarb is bubbling and tender.

Step 7: Cool and Slice

Patience is key for that perfect slice! Let your bars cool in the pan for at least 15 minutes. They’ll finish setting up and be much easier to serve—whether you prefer them warm with a fork or cool and cut into tidy squares.

How to Serve Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars

Garnishes

The simplest way to dress up these bars is with a light dusting of powdered sugar, but you can take it further with a dollop of softly whipped cream or creamy vanilla yogurt. Lemon zest adds a sunny pop if you want to play up the tartness. Each of these options makes the Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars even more tempting!

Side Dishes

If you’re serving these as a dessert, consider pairing them with a scoop of vanilla ice cream or a spoonful of thick ricotta. For a morning treat, a hot mug of tea or a cold glass of milk brings out their homey charm and complements their flavor.

Creative Ways to Present

For parties or potlucks, slice the bars into bite-sized squares and serve on a rustic wooden platter. You could even layer pieces in small mason jars with extra fruit for an adorable, portable trifle. Want to really impress? Drizzle with melted white chocolate and a sprinkle of toasted coconut for a modern twist on these Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars.

Make Ahead and Storage

Storing Leftovers

Once the bars are completely cool, store them in an airtight container at room temperature for up to two days or in the refrigerator for up to a week. The flavors deepen as they sit, and the oat layer stays delightfully chewy.

Freezing

Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars freeze beautifully! Cut cooled bars into squares, wrap each one tightly in plastic, and store them in a freezer-safe bag or container. They’ll keep for up to three months, making it easy to grab a homemade treat anytime.

Reheating

If you love your bars warm and fragrant, pop a bar into the microwave for about 10–15 seconds or warm a batch in a low oven for a few minutes. This brings back the just-baked aroma and makes the rhubarb even softer.

FAQs

Can I use frozen rhubarb instead of fresh?

Absolutely! If using frozen rhubarb, there’s no need to thaw—just scatter it straight over the base, but add an extra 5 minutes to the baking time to ensure everything is cooked through.

Can I use gluten-free flour?

Yes, a good all-purpose gluten-free blend substitutes perfectly in these bars, so everyone can enjoy Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars regardless of dietary needs.

How do I know when the bars are finished baking?

Look for the top to turn a light golden brown and for the rhubarb to be bubbling slightly around the edges. This is when you know the bars are done and ready to come out of the oven.

Can I add other fruits?

Of course! Strawberries are a classic pairing with rhubarb, or toss in a handful of raspberries or blueberries for a little extra color and sweetness in your bars.

Are these bars sweet or tart?

These Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars strike a lovely balance between sweet and tart—the brown sugar and butter keep things mellow, while the rhubarb gives that signature zing.

Final Thoughts

There’s just something irresistible about these Easy Old Fashioned 5-Ingredient Oatmeal Rhubarb Bars—they’re comforting, easy, and endlessly adaptable. Whether you’re baking for old friends or treating yourself, give them a try and let their rustic, home-baked charm brighten your table!

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