Rhubarb Oat Bars

Rhubarb Oat Bars are buttery, chewy bars layered with a sweet-tart rhubarb filling and a golden oat crumble. They’re easy to make, full of cozy flavor, and perfect for a simple summer dessert or snack.

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Course: Dessert, Snack

Cuisine: American

Keyword: Rhubarb Oat Bars

Prep Time: 15

Cook Time: 40

Cooling Time:: 5

Total Time: 1

Servings: Bars

Calories: 210kcal

Equipment

8×8-inch baking dish
Mixing bowls
Saucepan
Spatula
Measuring cups & spoons
Knife and cutting board

Ingredients

Rhubarb Filling:

4 cups chopped rhubarb fresh or frozen
1/2 cup sugar
1 tbsp water
Generous squeeze of lemon juice

Oat Bar Crust & Topping:

1 1/4 cups all-purpose flour
1 1/4 cups quick oats
2/3 cup sugar
1/4 tsp kosher salt
1/2 cup butter melted

Sugar Topping:

Cinnamon + sugar mix to sprinkle on top

Instructions

Step 1: Make the Rhubarb Filling

In a saucepan, combine the rhubarb, sugar, water, and lemon juice. Bring to a simmer over medium heat. Cook for about 10–12 minutes, stirring occasionally, until the rhubarb breaks down and thickens. Set it aside to cool slightly.
Tip: Keep stirring gently so it doesn’t stick to the bottom of the pan. It should look like a loose jam.

Step 2: Mix the Crust and Topping

In a bowl, stir together the flour, oats, sugar, and salt. Pour in the melted butter and mix until everything’s moistened. It’ll look crumbly, but should hold together when pressed.

Step 3: Assemble

Press about 2/3 of the oat mixture into a greased 8×8 pan to form the crust. Spread the rhubarb filling evenly over the crust. Sprinkle the remaining oat mixture on top.
Finish with a light dusting of cinnamon sugar.

Step 4: Bake

Bake at 350°F (175°C) for 35–40 minutes, until the top is golden and the filling bubbles at the edges.

Step 5: Cool and Cut

Let the bars cool completely in the pan before slicing. They’ll set up as they cool, so don’t rush this part.

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