Crazy, I know, to post a recipe calling for rhubarb in November, but two things: One, this is really a post about crumb cake, and you can sub berries or cherries or sort of anything your heart desires for the rhubarb (you could even leave the fruit out altogether and make a straight-up, fab-o, crumb cake). And two, we found rhubarb growing (against all odds) in the garden about a month ago and I sort of/kind of had to make something with it.
At first I was thinking buckle, cause I love the name so much. Then I was thinking coffee cake, cause I love this crumb cake so much (and have actually made it kind of a lot in the 8 years since I first stumbled upon it in the newspaper). and so, not surprisingly, my first version of this crumb cake (made with creme fraiche), was very much a member of the buckle/coffee cake family. it was awfully yummy, with warm pockets of tart/sweet, rhubarb, and yet awfully dense (due to the creme fraiche, I’m thinking). 
And then it hit me: I wanted a lighter, fluffier — dare i say moister — cake than a buckle or coffee cake, but one that still had a big-ole topping of crumb. In other words, I wanted a crumb cake. As a kid, my first exposure to crumb cakes (incorrectly labeled “coffee cakes”) was to the packaged (and need I say delicious) variety. But more recently, I had crossed paths with this particular crumb cake. The crumbs of a crumb cake all seem to call for melted butter, but I wasn’t going in that direction (smooshing cold cubes of butter into flour and sugar with your fingers is what crumb topping is all about for me). Plus the cakes of a crumb cake run the gamut. I knew mine would have oil for moistness and cake flour in place of some of the all-purpose, as well as buttermilk, rather than the aforementioned creme fraiche, for the light and fluffy cake-qualities I was after.
My resulting cake? The crumb cake of my dreams: A super moist, soft and fluffy cake with chunks of rhubarb suspended throughout, and the most buttery of crumb toppings, complete with a combo of sugars and just a touch of spice (ie: cinnamon). I’m not going to lie, the packaged mini crumb cakes of my childhood did cross my mind as I polished off my first piece of rhubarb crumb tastiness, but only in the best of ways, as I was ever so pleased that my not-so-seasonal, but oh-so-tasty cake, brought back memories of the packaged yumminess of my childhood.
Rhubarb Crumb Cake
Ingredients
For the crumb
- 2 sticks salted butter cold (if using unsalted, add 1/2 tsp salt)
- 1 1/2 cups all purpose flour
- 3/4 cup light brown sugar
- 3/4 cup granulated sugar
- 1/2 tsp cinnamon
For the cake
- 4 cups chopped rhubarb chopped into 1/2-to-1-inch pieces
- 1 Tbsp arrowroot
- 1 1/2 cups all purpose flour divided
- 1 1/2 cups cake flour
- 2 tsp baking powder
- 1/2 tsp baking soda
- 1 tsp salt
- 1/2 stick unsalted butter, room temp
- 4 Tbsp oil such as canola
- 1 Tbsp pure vanilla extract
- 3/4 cup light brown sugar
- 1/2 cup granulated sugar
- 2 large eggs
- 3/4 cup buttermilk
Instructions
- Preheat the oven to 375 degrees. Spray and paper and spray again a 13x9x2-inch baking pan. Set aside.
To make the crumb
- Cut the butter into small cubes. Set aside.
- Place all of the dry ingredients in a medium-sized bowl and whisk to combine. Add the butter, and using your hands, incorporate the butter into the dry ingredients, until a variety of different sized crumbs form (some big, some not) and there is no more loose flour or sugar. Place the crumb in the refrigerator.
To make the cake
- Place the rhubarb in a medium sized bowl and lightly spray with cooking spray. Toss with the arrowroot and 1/4 cup of the all-purpose flour until all of the rhubarb is coated. Place in the freezer until ready to use. If you want to avoid oil, you can skip the cooking spray but it helps the flour stick.
- Place the remaining all-purpose flour, cake flour, baking powder, baking soda, and salt in a medium sized bowl and whisk to combine.
- Cut the butter into pieces, and place in the bowl of a stand mixer fitted with the paddle attachment. Cream the butter on medium-high until smooth. Stop the mixer, scrape the bowl with a rubber spatula, reduce the speed to medium, and add the oil and vanilla and cream until incorporated. Add the sugars gradually, stopping the mixer and scraping down the bowl periodically, until all of the sugar is added.
- Increase the speed of the mixer to medium-high and cream the butter, oil, vanilla, and sugar for at least 5 minutes until quite light and fluffy, stopping and scraping, occasionally. Reduce the speed to medium, add the eggs, one at a time, scraping down the bowl after each addition.
- Reduce the mixer speed to low and add the dry ingredients in three installments, alternating with the buttermilk, beginning and ending with the dry. Scrape the bowl after the second addition of the dry. Stop creaming all together when the batter still has a bit of dry flour throughout.
- Remove the bowl from the mixer and add the rhubarb. Using a rubber spatula fold the rhubarb into the batter. Transfer the batter to your prepared pan, smoothing the top with an offset spatula. Remove the crumbs from the freezer, and cover the cake with them, pinching the crumbs between your fingers to form assorted-sized balls of buttery/flour-y deliciousness.
- Place the cake in the preheated oven and bake for 20 minutes. Reduce the heat to 350 degrees and bake for about 40 minutes more, or until a toothpick comes out with only a moist crumb or two, rotating the cake halfway through the baking time.
- Let the cake come to room temp before slicing it and serving. Or serve it warm with a dollop of whipped cream. The cake is very moist and will last on the counter for a few days, tightly wrapped. The slices also freeze well and can be reheated in a 350-degree oven, wrapped in tinfoil.
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2 replies on “Rhubarb Crumb Cake”
Hi Jessie,
Do you think this would work with frozen rhubarb? None growing in my garden, sadly.
If so, would you defrost it and drain it, then toss with the arrowroot and rechill, or just toss the frozen pieces?
The cake looks irresistible!
Yes! It will totally work with frozen (I made it once with frozen and once with fresh – and there was no difference). Just toss it with the arrowroot, as stated in the recipe, and then stick back into the freezer. Let me know how it turns out!!