Rhubarb Shortbread Crumble Bars

Sliced rhubarb bars on parchment paper next to a large knife and flowers.

5 from 9 votes

Simple yet insanely delicious rhubarb bars with a buttery shortbread crust, sweet and tart rhubarb custard filling, and finished with a cinnamon oatmeal streusel topping. All you could ever want in a rhubarb bar! Plus, they're so easy to make!

Prep Time15

Cook Time1

Total Time1 15

Course: Dessert

Cuisine: American

Servings: bars

Calories: 285kcal

Author: Rachel Kochlin

Equipment

8x8 inch baking dish (or double the recipe for a 9x13)
mixing bowls

Ingredients

Shortbread crust

1 ¼ cups all-purpose flour
⅓ cup powdered sugar
⅛ teaspoon salt
6 tablespoons salted butter, melted

Rhubarb custard filling

1 cup granulated sugar
¼ cup all-purpose flour
⅛ teaspoon salt
2 eggs
¼ cup heavy whipping cream
2 ½-3 cups rhubarb chopped
1 teaspoon vanilla extract

Crumble topping

¼ cup all-purpose flour
¼ cup old fashioned oats
¼ cup brown sugar packed
¼ teaspoon baking powder
¼ teaspoon cinnamon
¼ cup cold salted butter cubed

Instructions

Heat oven to 350°F and line an 8x8 inch baking dish with parchment paper.
Whisk together the flour, powdered sugar, and salt. Pour in the melted butter and mix until combined. Sprinkle the dough into your lined baking dish and press down into an even layer. Bake for about 10-12 minutes or until a light golden color.
While the crust bakes, make the filling. In a large bowl, whisk together the sugar, flour, and salt. Add in the eggs and heavy whipping cream, then whisk until combined. Stir in the rhubarb and pour over the crust. Bake for 25 minutes - the filling will finish baking after you add the streusel.
Meanwhile, make the crumble topping. In a small bowl, whisk together the flour, oats, and brown sugar. Add the cold butter and use a pastry blender to work the butter into the mixture until combined but crumbly - store in the fridge to keep cool until it's time to sprinkle over the bars. Evenly spread the crumble over the rhubarb filling. If desired, top with some extra slices of rhubarb.
Continue to bake for another 20-25 minutes until the filling is set and no longer jiggly.
Let cool for 30-60 minutes then cover and refrigerate to cool completely before slicing into bars.

Notes

Substitutions & variations:

To make the bars more tart. I feel like these bars are the perfect balance between sweet and tart, but if you prefer a more tart rhubarb filling, increase the amount of rhubarb to 3 or 3 ½ cups or decrease the sugar to ¾ cup.

Add fruit. To make strawberry rhubarb bars, swap 1 cup of rhubarb for 1 cup of sliced strawberries, or even raspberries.

Using frozen rhubarb. Frozen rhubarb contains quite a bit of liquid, so be sure to thaw and drain it first.

Double the recipe for a 9x13-inch baking dish. Making bars for a crowd? Just double the recipe and use a 9x13-inch baking dish. The cook time will stay relatively the same. Bake the bars until the center is set and no longer jiggly.

Make it look pretty. After you sprinkle the streusel crumble over the bars, you can also sprinkle on some slices of rhubarb that will bake into the streusel making the bars look extra pretty! Totally optional.

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