Rhubarb Crumb Cake! Three words that definitely belong together. Soft buttermilk cake is loaded with chunks of fresh rhubarb and crowned with brown sugar crumb topping.

an overhead view of a crumb cake sprinkled with powdered sugar

Calling all rhubarb lovers! You will want to enjoy this cake when our favorite vegetable, yes vegetable, is in season.

This cake is not shy with the rhubarb, there’s a whole pound of it in the batter. That is a full 16 oz of vegetables in this cake. I think that pretty much makes it a health food, no?

This cake would be wonderful for breakfast, brunch, snack time or any time at all.

Ingredient Notes

Cake flour – Low protein cake flour makes the softest cakes.
Buttermilk – Acidic buttermilk tenderizes the cake crumb and adds great flavor.
Fresh Rhubarb – Choose rhubarb that is plump and crisp. Do not use frozen rhubarb because it will exude too much water into the cake.

How to make Rhubarb Crumb Cake:

a hand grabbing a clump of brown sugar cake topping

The crumb topping will look like wet sand after it’s mixed. Grab a handful of the topping to form a large clump.

chopped rhubarb on a green cutting board with a knife

Chop the rhubarb into 1/2″ chunks

all the components of rhubarb crumb cake ready to assemble

Spread a cup of the batter on the bottom of the pan.
Fold the rhubarb into the remaining batter.

a hand breaking clumps of crumb topping over cake batter

Break the large clumps of topping into marble sized pieces over the batter.

The crumbs should completely cover the surface of the cake

Pastry Chef tips for making Rhubarb Crumb Cake:

Mix the crumb topping until it resembles wet sand. It might look dry, but if you grab a handful it should form a nice clump.
Spread a cup of plain batter into the pan before adding the rhubarb. This will form a solid base for the cake so it doesn’t come apart as you cut it.
When you fold the rhubarb into the batter you might think it’s a mistake. It’s not. There is about the same amount of rhubarb as batter.
To check if the cake is baked in the middle, lift one of the crumbs from the center and insert a toothpick into the cake. It should come out clean.
The cake is best the day it is baked, but will keep at room temperature for 2-3 days. The topping will soften after a day.

a piece of rhubarb crumb cake on a small white plate

If you keep a starter, you’ll love this Sourdough Crumb Cake. During blueberry season you can make this Blueberry Crumb Cake.

I am obsessed with the unique flavor of rhubarb. You too? Here are a few more recipes for you to try:

If you love this recipe as much as I do, I’d really appreciate a 5-star review.

Print Recipe

4.80 from 5 reviews

Rhubarb Crumb Cake Recipe

By: Eileen Gray

Soft buttermilk cake loaded with fresh rhubarb & crowned with brown sugar crumb topping.

Prep Time30

Bake Time45

Total Time1 15

16 portions

Ingredients

Crumb Topping

6 ¾ oz cake flour (1 ½ cups)
5 ¼ oz brown sugar (⅔ cup)
¼ teaspoon salt
2 teaspoons cinnamon
1 teaspoon ground ginger
4 oz unsalted butter (room temperature)

Cake Batter

1 large egg
1 yolk
6 oz buttermilk (¾ cup, divided)
1 teaspoon vanilla
9 oz cake flour (2 cups)
6 oz granulated sugar (¾ cup)
1 ½ teaspoons baking powder
1 teaspoon ground ginger
¼ teaspoon salt
4 oz butter (room temperature)
1 pound rhubarb (cut into ½" dice (about 3 cups))

Instructions

Preheat the oven to 350 °F. Butter and flour a 9" square cake pan. Cut an 8"x16" piece of parchment paper and line the pan in one direction, leaving a short overhang on each side.

Crumb Topping

Combine 6 ¾ oz cake flour, 5 ¼ oz brown sugar, ¼ teaspoon salt, 2 teaspoons cinnamon, and 1 teaspoon ground ginger into the bowl of a stand mixer or into a large mixing bowl. Mix on low speed until completely combined. With the mixer running, add 4 oz unsalted butter in chunks and continue to mix until the topping looks like wet sand. Remove from the mixer and transfer to a small bowl by squeezing handfuls to create large clumps. Set aside while you mix the batter.

Batter

Combine 1 large egg, 1 yolk, 6 oz buttermilkalf the buttermilk and 1 teaspoon vanilla in a small bowl and set aside.
Sift 9 oz cake flour, 6 oz granulated sugar, 1 ½ teaspoons baking powder, 1 teaspoon ground ginger, and ¼ teaspoon salt into the bowl of a stand mixer or into a large mixing bowl. With the mixer running on low speed, add 4 oz butter and the remaining buttermilk. Mix until completely combined. Scrape the bowl and beater. Mix on medium speed for 2-3 minutes to lighten the batter.
Scrape the bowl and add the egg mixture in two batches, scraping between additions. Remove 1 cup of the batter and spread it into the pan. By hand, fold the rhubarb into the remaining batter. Spread the batter with the rhubarb into the pan.
Sprinkle the crumb topping over the batter, breaking it into marble sized clumps as you scatter it over the cake batter.
Bake until a toothpick inserted in the center comes out clean, about 45-50 minutes. Cool at least 30 minutes in the pan. Use the parchment to carefully lift the cake out of the pan.
Cool completely on a wire rack

Equipment

My Book

KA Stand Mixer

9 x 9 Brownie Pan with Lid

Parchment Sheets

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Nutrition

Have you tried this recipe?Mention @eileen.bakingsense or tag #bakingsense!

anita seah

Tuesday 8th of September 2020

hi Eileen

im really new to baking what is cake flour ? in australia we use self raising flour to make cakes would that be the same? thank you

Eileen Gray

Cake flour is a lower protein flour that makes a softer cake. I suppose you could use self rising flour and leave out the salt and baking powder from the recipe. Otherwise, for every cup of cake flour use 3/4 cup of all purpose flour plus 2 tablespoon of corn starch.