Name: Amish Oatmeal Rhubarb Bars Recipe
Prep time: 15 min
Cook time: 35 min
Total time: 50 min
Cuisine: Amish
Ingredients: 1 ½ cups old-fashioned oats; 1 ½ cups all-purpose flour; 1 cup brown sugar, packed; ½ tsp baking soda; ¼ tsp salt; ¾ cup (1 ½ sticks) cold unsalted butter, cut into cubes; 3 cups chopped rhubarb; 1 cup granulated sugar; 2 tbsp cornstarch; ½ cup water; 1 tsp vanilla extract

Jump to Recipe·5.2 from 9 reviews

Imagine biting into a bar that’s the perfect balance of cozy, farmhouse comfort and a delightful zing—that’s exactly what you get with Amish Oatmeal Rhubarb Bars. Each mouthful layers the nutty chew of oats, a buttery brown sugar crumble, and a tart, jammy rhubarb center brightened with a hint of vanilla. Not only do these bars bring together simple pantry staples and a garden favorite, but they also deliver a rustic treat that feels like a warm hug and a celebration of rhubarb’s zippy flavor. Whether you’re nostalgic for family recipes or keen to try an old-fashioned dessert with a sweet-tart twist, these bars always hit the spot.

Amish Oatmeal Rhubarb Bars Recipe - Recipe Image

Ingredients You’ll Need

The beauty of Amish Oatmeal Rhubarb Bars is in their simplicity—each ingredient has a delicious job to do, from giving structure and body to delivering that signature burst of tang. Grab your favorite mixing bowls, and let’s see why these basics are anything but boring!

Old-fashioned oats: These give the bars their hearty chew and rustic character—avoid quick oats for best texture.
All-purpose flour: Just enough to bind the bars together without making them dense.
Brown sugar, packed: Lends depth and subtle molasses notes to the crumble and crust.
Baking soda: A touch for leavening, ensuring the bars aren’t flat or heavy.
Salt: A tiny amount brings out sweetness and balances the tartness of rhubarb.
Cold unsalted butter, cut into cubes: The key to a melt-in-your-mouth, tender crumb that toasts up golden in the oven.
Chopped rhubarb: The star ingredient—choose crisp, ruby stalks for the boldest flavor and prettiest color.
Granulated sugar: Sweetens the rhubarb filling just enough to balance the natural tartness.
Cornstarch: Thickens the filling so it doesn’t ooze out of your bars, holding everything together.
Water: Helps cook down the rhubarb, creating a luscious, jam-like consistency.
Vanilla extract: Adds warmth and rounds out all the flavors in every bite.

How to Make Amish Oatmeal Rhubarb Bars

Step 1: Preheat the Oven and Prepare Your Pan

Before you get started, preheat your oven to 350°F (175°C). This way, it’s ready the moment your bars are assembled. Grease a 9×13 inch pan with butter or a spritz of baking spray, or line it snugly with parchment paper. Parchment paper not only makes for easy clean-up but also helps lift the bars out fuss-free once they’re baked and cooled.

Step 2: Make the Oat Crumble Mixture

In a large mixing bowl, combine the oats, flour, packed brown sugar, baking soda, and salt. Stir everything together until evenly distributed. Now, work in the cold, cubed butter using a pastry cutter, fork, or your fingertips. The goal is a crumbly mixture that clumps together when pressed—think pebbles and sandy bits. This dreamy combination will serve as both the base and the topping of your Amish Oatmeal Rhubarb Bars, providing layers of chewiness and crunch.

Step 3: Prepare the Rhubarb Filling

In a medium saucepan, stir together the chopped rhubarb, granulated sugar, cornstarch, and water. Turn the heat to medium and cook, stirring constantly, until the mixture thickens to a glossy, jammy consistency—about 5 to 7 minutes. Rhubarb will break down as it cooks, soaking up the sugar while still keeping its beautiful tart edge. Once that magic texture is achieved, remove from the heat and stir in the vanilla extract for a wonderful depth of flavor.

Step 4: Layer and Assemble the Bars

Pour and press half the oat-butter mixture firmly into the bottom of your prepared pan to create a solid yet tender crust. Don’t be shy—use your hands or a measuring cup to really pack it down. Next, spread the rhubarb filling evenly over the crust, making sure each corner gets a generous amount. Sprinkle the rest of the oat crumble on top, gently pressing to anchor the topping but not flatten it completely.

Step 5: Bake and Cool

Slide the pan into your preheated oven and bake for 30 to 35 minutes, or until the top is beautifully golden and your kitchen smells heavenly. You’ll know they’re ready when the filling bubbles merrily around the edges. The hardest part? Letting them cool completely before slicing—this patience rewards you with neat bars and perfectly set filling.

How to Serve Amish Oatmeal Rhubarb Bars

Garnishes

For a finishing touch, sprinkle your cooled bars with a dusting of powdered sugar for a dreamy, bakery-style look. You can also drizzle a little vanilla glaze over the top or add a dollop of whipped cream to each serving. These small touches make your Amish Oatmeal Rhubarb Bars feel extra-special, perfect for guests or a cozy dessert night.

Side Dishes

While these bars shine solo, they pair beautifully with a few simple sides. A scoop of vanilla ice cream always complements the tart rhubarb, and a mug of hot tea or coffee is a classic pairing that rounds out the experience. For brunch gatherings, serve with fresh seasonal fruit or a bowl of creamy Greek yogurt for a bright, satisfying spread.

Creative Ways to Present

Cutting the bars into bite-sized squares turns them into party-ready finger food. You could also layer crumbled bars in a glass with whipped cream and extra rhubarb compote for a show-stopping parfait. For picnic baskets or bake sales, wrap individual bars in parchment and tie with twine for rustic, sweet gifts that impress before the first bite.

Make Ahead and Storage

Storing Leftovers

Amish Oatmeal Rhubarb Bars are just as lovely the next day—and maybe even better as the flavors mingle! Store bars in an airtight container at room temperature for up to 2 days. If your kitchen runs warm or you want to stretch them a bit longer, pop them in the fridge where they’ll keep fresh for up to 5 days.

Freezing

If you’re making a big batch or simply want to save some for later, these bars freeze wonderfully. Once fully cooled, cut them into individual portions and wrap each bar in plastic wrap. Store in a freezer-safe bag or container for up to 2 months. Thaw at room temperature or in the fridge overnight before serving.

Reheating

While Amish Oatmeal Rhubarb Bars are tasty cold or at room temperature, you can gently rewarm them for an extra comfort factor. Place a bar on a microwave-safe plate and heat for 10-15 seconds or until just warmed through. For a crispy top, heat briefly in a low oven (around 300°F) for a few minutes—you’ll revive that lovely toasty crumble.

FAQs

Can I use frozen rhubarb instead of fresh?

Absolutely! If using frozen rhubarb, there’s no need to thaw, but you may want to add an extra teaspoon of cornstarch to help set the filling since frozen rhubarb often contains a bit more moisture.

What if I don’t have old-fashioned oats?

You can substitute quick oats in a pinch, but the texture will be softer and less rustic. Steel-cut oats aren’t recommended, as they won’t soften enough during baking.

Can I make Amish Oatmeal Rhubarb Bars gluten-free?

Yes! Simply swap the all-purpose flour for your favorite cup-for-cup gluten-free flour blend, and make sure your oats are certified gluten-free. The results are still deliciously tender and chewy.

Is it possible to reduce the sugar?

You can cut the sugar down a bit in both the crumble and filling if your rhubarb isn’t extremely tart or you prefer a less sweet dessert. Just note the bars may be a bit less rich and the tartness of the rhubarb will stand out more.

What’s the best way to cut the bars neatly?

Let the bars cool completely in the pan—overnight is even better. Use a sharp knife, and wipe it clean between cuts for picture-perfect slices every time. If using parchment, lifting the whole slab out first makes things even easier.

Final Thoughts

If you’re looking for that irresistible mix of old-fashioned charm and bright, lively flavor, Amish Oatmeal Rhubarb Bars are a must-try. Gather your favorite people, stir up these cozy, sweet-tart treats, and let every bite remind you of the simple joys in baking. I can’t wait for you to fall in love with them, just like I did!