Name: Rhubarb Crumb Bars
Prep time: 15 min
Cook time: 45 min
Total time: 1 h
Yield: 16 bars
Cuisine: American
Ingredients: 1/2 cup butter (room temperature); 1 cup confectioners' sugar; 2 large eggs (at room temperature); 1/2 teaspoon pure vanilla extract; 3/4 cup flour; 1/2 teaspoon baking powder; 1/4 teaspoon salt; 1/2 pound rhubarb (cut into 1/2-inch pieces); 1 tablespoon brown sugar; 1/4 cup all-purpose flour; 6 tablespoon butter (melted); 1 cup all-purpose flour; 1/2 cup packed brown sugar; 1/4 teaspoon salt

This dessert starts with a soft cake, a layer of rhubarb, then a sweet and crunchy crumble!Rhubarb crumbbars are a light and delicious treat that are easy to make and enjoy.

square portion of rhubarb crumble served on a round white plate.

Rhubarb is often an underrated ingredient that many people tend to forget to use in sweet treats. You may have heard of rhubarb pie, but there are so many other ways to use this unique ingredient! In this recipe, the rhubarb makes a perfectly tart and bright layer that gives these bars a delightful balance of sweet and sour flavors.

The bars have an amazing flavor; they are light enough to be served as a sweet breakfast or lunch, and are sweet enough to eat for dessert. The soft cake paired with the crunchy topping makes for a wonderful combination that everyone will enjoy. There is so much to love about these rhubarb crumb bars!

You can also tryBlueberry Pie Cookie BarsandRaspberry Streusel Barsbecause they both have a fruit layer and a crumb topping. Something about tangy fruits and sweet topping makes for delicious desserts every time.

glass dish with baked rhubarb crumb bar recipe inside.

Why You’ll Love This Recipe

These bars feature a gooey rhubarb layer and a crunchy cake layer.
The combination of sweet and tangy flavors packs a delicious punch.
Quick and easy to make.

What is Rhubarb?

Rhubarb is a spring vegetable that typically has a green or red color, and although they have no relation, looks similar to celery with its long and thin shape. It is very sour when eaten raw, but has a pleasant tart flavor when cooked. Rhubarb is used for many different dishes both savory and sweet. It is often used in pastries, jams, or desserts because sugar will balance out the flavor nicely!

Recipe Ingredients

portion bowls each with raw ingredients to make rhubarb crumb bars.

For the Cake

Flour—All-purpose. This will be used in each layer of the dessert.
Butter—Softened but not melted. For a rich and tender crumb!
Confectioners Sugar—To keep the cake soft and add a subtle sweetness to the base.
Eggs—Room temperature.
Vanilla Extract—To enhance the flavor of the cake base.
Baking Powder—For a light and airy cake.
Salt—Helps all of the flavors pop.
Brown Sugar—Adds a rich sweetness to your rhubarb and crumb topping.
Rhubarb—Cut into small pieces. For a bright, tart flavor!

See the recipe card for full information on ingredients and quantities.

How to Make Rhubarb Crumb Bars

clear mixing bowls with raw ingredients to make rhubarb crumb bars.

clear mixing bowl in the process of making rhubarb crumb bars.

Step #1.Preheat the oven. Grease a baking dish and set aside. For the cake, beat the butter and sugar together in a small bowl until light and fluffy.

Step #2.Add the egg and vanilla and stir well to combine.

glass dish in the process of making rhubarb crumb bars.

Step #3.Add the flour, baking powder, and salt. Once mixed, add the batter to the greased pan.For the rhubarb layer, add the rhubarb, brown sugar, and flour into a small bowl and toss to combine.

Step #4.Evenly distribute the rhubarb layer over the cake layer. Bake the cake. While the cake is baking, make your crumb topping. In a bowl, melt the butter. Add the flour, brown sugar, and salt. Stir to combine until the mixture is thick. After the cake is partially cooked, remove it from the oven and sprinkle the crumb topping over the rhubarb layer. Continue to bake the cake until it is done. Allow the cake to cool.

Recipe FAQs

Are powdered sugar and confectioners sugar the same thing?

No, they are not the exact same thing but they are similar! They are both made from finely ground white sugar, but confectioners sugar also contains a little bit of starch. This usually helps the sugar from clumping when it sits for long periods of time. It also keeps the sugar from melting if used as a topping for a pastry. The two often get confused, and if you are baking treats at home it is not a big deal if you swap them!

Do I have to wait to add the crumble?

Yes, it is important to allow the cake to bake for at least 15 minutes before you add the crumble topping. This is so that the crumble does not sink into the liquidy batter and rhubarb layer. The cake will set enough in 15 minutes to allow the crumble to stay on top and crisp up nicely. If you add it at the same time as the rhubarb layer, it will get lost in the cake rather than become a sweet crust for the bars.

How to Store Rhubarb Crumb Bars

Any leftover crumb bars can be stored at room temperature or in the fridge. Be sure to transfer the bars into an airtight container to keep them fresh. They will stay good for up to 4 days, if they last that long! You can heat them up in the microwave for a few seconds, or enjoy them at room temperature.

glass dish with baked rhubarb crumb bar recipe cut into squares.

Expert Tips

When measuring your brown sugar,be sure that it is packed into the measuring cup or spoon, to remove any air pockets and get the right measurement!
Break your thick crumb topping into pieces that are about the size of the end of your pinkie finger, then evenly distribute it over the cake.
Thetotal baking time for the cake will be about 45-50 minutes.
Allow the cake to cool for at least an hourbefore cutting into it and serving so that it can fully set.