Tangy Rhubarb Dessert Bars with Buttery Crust

If you love rhubarb, these bars are a perfect way to enjoy it. The filling balances rhubarb’s bright tartness with a touch of sugar and strawberry jam, while the oat-and-flour crumble provides a tender, buttery base and crisp top.

Rhubarb’s season is short—one of the earliest spring harvests—so when it’s available, it’s worth making a batch of bars, crisps, or sauces to enjoy while the stalks are tender and flavorful.

The Best Rhubarb Bars

Sweet-tart balance. These bars add just enough sugar and jam to soften rhubarb’s tart edge while preserving a lively flavor.

Layered texture. A cinnamon-spiced oat crust forms the base, a jammy rhubarb filling adds brightness, and a crumb topping gives a satisfying finish.

Easy to make. No rolling pie dough—simply simmer the filling, mix the crust/topping, press half into the pan, bake, add filling, top with crumbs, and finish baking. Serve warm with ice cream for an extra treat.

Ingredient Notes

• Granulated sugar: Calms the rhubarb’s tartness.
• Cornstarch: Thickens the filling; find it in the baking aisle.
• Rhubarb: Discard leaves. Choose firm, smaller stalks for tenderness. Color (red or green) doesn’t affect flavor. Frozen rhubarb works, though fresh is juicier.
• Strawberry jam: Adds sweetness and pairs naturally with rhubarb.
• Quick oats: Use quick oats or pulse rolled oats in a food processor to mimic the texture.
• All-purpose flour: Measure by lightly spooning into the cup and leveling with a straight edge.
• Light brown sugar: Gives a gentle caramel note without strong molasses flavor.
• Ground cinnamon: Adds warmth; cardamom can be substituted for a different flavor profile.
• Unsalted butter: Soften to room temperature for easy cutting into the dry ingredients.

How To Make Rhubarb Bars

Prep: Preheat the oven to 325°F (163°C). Lightly spray a 9 x 13-inch pan, line it with parchment, and spray the parchment so it stays in place.

Make the filling: In a small saucepan combine sugar and cornstarch, then stir in rhubarb, jam, and water. Bring to a simmer over medium heat, stirring constantly. Reduce heat and cook until the rhubarb breaks down and the mixture is thick and jammy. Cool slightly; you should have about 2½ cups of filling.

Mix crust ingredients: In a large bowl combine oats, flour, brown sugar, cinnamon, and salt. Cut in softened butter with a pastry cutter, two forks, or your fingers until the mixture becomes crumbly and holds together when pressed.

Assemble and bake: Reserve 2 cups of the crumb mixture. Press the remaining crumbs evenly into the prepared pan and bake for 10 minutes. Remove from the oven, spread the cooled rhubarb filling over the crust, then sprinkle the reserved crumbs on top and gently press with a spoon. Return to the oven and bake about 50 minutes, until golden and set.

Cool and serve: Let the bars cool completely before lifting them from the pan using the parchment. Slice with a sharp knife and serve at room temperature or slightly warm.

Recipe Variations

• Change the jam: Swap strawberry with raspberry, blueberry, blackberry, or peach jam for a different berry note.
• Swap spices: Use ground cardamom instead of cinnamon for a Scandinavian twist (use the same amount).
• Try cake instead: If you prefer cake, consider a streusel-topped rhubarb cake with similar flavors and texture.

Make Ahead Ideas

You can prepare the rhubarb filling up to 2 days ahead and refrigerate in an airtight container. Warm slightly before spreading if it thickens in the fridge.

Storage Suggestions

Store bars in an airtight container at room temperature for 4–5 days or refrigerate up to 7 days.

To freeze: wrap each bar tightly in plastic wrap and foil, place in a freezer-safe container, and freeze up to 3 months. Thaw in the refrigerator or at room temperature.