Name: Delicious Oatmeal Rhubarb Bars
Prep time: 20 min
Cook time: 30 min
Total time: PT-487189H59M2S
Cuisine: Dessert
Ingredients: 2 cups stale bread or brioche, cut into 1″ cubes; 1 stalk fresh rhubarb (or 2 small stalks), cut into 1″ pieces; 1 tbsp melted butter; 1½ cups milk; ½ cup heavy cream; 1 egg; 1 tbsp granulated sugar; ¼ tsp ground nutmeg; 2 tbsp rhubarb compote (see note); Homemade or store-bought custard; ½ tsp fresh orange zest

Why You’ll Love This Recipe

I adore how these bars combine the bright tartness of rhubarb with the cozy, chewy texture of oats. With a simple crumb-like crust and topping made from one oat mixture, they’re easy to prep but taste like homemade love. They also handle substitutions—fresh or frozen rhubarb—and are perfect for breakfast, snack time, or dessert

ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

2 cups all‑purpose flour
1 ½ cups old‑fashioned rolled oats
1 cup packed brown sugar
1 tsp ground cinnamon
½ tsp kosher salt
1 cup unsalted butter, melted
4 cups chopped rhubarb (fresh or thawed frozen)
⅔ cup granulated sugar
3 Tbsp cornstarch
1 Tbsp lemon juice
½ tsp vanilla extract (optional)

directions

I preheat the oven to 350 °F (175 °C) and line a 9×13″ pan with parchment or grease it.
In a bowl, I mix flour, oats, brown sugar, cinnamon, and salt. I stir in melted butter until the mixture clumps.
I reserve about 1½ cups of this mixture for the topping, then press the rest firmly into the bottom of the pan.
I combine chopped rhubarb, granulated sugar, cornstarch, lemon juice, and vanilla in another bowl, tossing to coat evenly.
I spread the rhubarb filling over the crust layer.
I sprinkle the reserved oat mixture evenly on top.
I bake for 25–35 minutes, until the top is golden and the filling bubbles around the edges
I let the bars cool completely—ideally 2 hours—so they set properly before slicing

Servings and timing

Servings: 12–16 bars (9×13 pan)
Prep time: ~20 minutes
Bake time: ~30 minutes
Cooling time: ~2 hours
Total time: ~3 hours

Variations

Add berries: I toss in ½ cup strawberry or raspberry jam with the rhubarb filling—or stir in fresh berries before baking
Nutty crunch: Sometimes I stir in 1 cup chopped pecans or walnuts for added texture
Spice twist: I blend a pinch of ground ginger or nutmeg into the filling for warm depth
Gluten‑free option: I swap the flour for a 1:1 gluten‑free baking mix and the oats are gluten‑free certified .

storage/reheating

I store bars in an airtight container at room temperature for up to 3 days or refrigerate for up to 5 days. They soften over time, but still taste great. I don’t recommend freezing, as the oat topping gets soggy . To serve warm, I microwave a bar for ~15 seconds or pop it in a 300 °F oven for a few minutes.

FAQs

Can I use frozen rhubarb?

Yes—I thaw and drain frozen rhubarb first, then follow the recipe. It works just as well as fresh .

Do I need to pre-cook the rhubarb filling?

No—the cornstarch and baking time are enough to cook and thicken the filling.

How do I keep the bars from falling apart?

Let cooling time be long—at least 2 hours—so the filling sets and binds layers solidly

Can I make these in a smaller pan?

Yes—a 9×9 pan works too; bake an extra 5–10 minutes to compensate for the thicker bars.

Are these bars freezer-friendly?

I don’t freeze them; the texture doesn’t hold up well. Instead, I tightly wrap individual slices and freeze them short-term, then thaw at room temp.

Conclusion

I love how these Oatmeal Rhubarb Bars bring a burst of bright rhubarb flavor into a comforting, oat-filled treat. They’re easy to make, full of pantry-friendly ingredients, and flexible—perfect to enjoy warm with ice cream or later with tea. They’re one of my favorite ways to celebrate rhubarb season.