This cake kicks butt. It’s been on my radar for quite some time so when I saw a gorgeous pile of fresh picked rhubarb at the market, I just knew it was meant for this recipe. The crust is crumbly with butter and the fruit gets jammy in pockets and sticky around the corners and the cake itself is lighter than light and so, so moist. It’s pretty much spring on a dessert plate and if you are swooning right now, you’d be correct.
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Crumbly Rhubarb Cake
- Total Time: 1 hour 15 minutes
- Yield: 4 1x
Description
This cake kicks butt. It’s pretty much spring on a dessert plate, and if you are swooning right now, you’d be correct.
Ingredients
rhubarb filling:
- 1/2 lb (225 g) rhubarb, trimmed (about 2 stalks)
- 1 tbsp fresh orange zest
- 1/4 cup (60 ml) sugar
- 2 tsp cornstarch
- 1 vanilla bean, sliced lengthwise with a paring knife and seeds scraped out
for the crumbs:
- 1/3 cup (80 ml) dark brown sugar
- 1/3 cup (80 ml) granulated sugar
- 1 tsp ground cinnamon
- Pinch of salt
- 1/2 cup (120 ml) melted butter
- 1 3/4 cup (420 ml) cake flour
for the cake:
- 1/3 cup (80 ml) sour cream
- 1 large egg
- 1 large egg yolk
- 2 tsp vanilla extract
- (or one more vanilla bean)
- 1 cup (240 ml) cake flour
- 1/2 cup (120 ml) sugar
- 1/2 tsp baking soda
- 1/2 tsp baking powder
- 1/4 tsp salt
- 6 tbsp softened butter, cut into 8 pieces
Instructions
- Preheat oven to 325 degrees F and butter an 8-inch square baking dish. Slice the rhubarb 1/2 inch thick and toss with the orange zest, sugar, cornstarch, and vanilla bean seeds. Set aside.
- Next, make the crumbs. In a large bowl, whisk together the sugars, cinnamon, salt, and butter until the mixture is smooth. Stir in flour. It will look like a solid dough.
- To prepare the cake, stir together the sour cream, egg, egg yolk, and vanilla. Using a mixer fitted with the paddle attachment: mix together the flour, sugar, baking soda, baking powder and salt. Add butter and a spoonful of sour cream mixture and mix on medium speed until the flour is moistened. Increase speed and beat for 30 seconds. Add remaining sour cream mixture in two more batches, beating for 20 seconds after each addition. Separate out 1/2 cup of batter and set aside.
- Scrape the remaining batter into prepared baking dish. Spoon rhubarb over the batter and dollop previously set-aside batter over rhubarb. This doesn’t need to be even.
- Using your fingers, break topping mixture into big crumbs, about 1/2 inch to 3/4 inch in size and spread over cake. Bake for around 45-55 minutes or until a toothpick inserted into center comes out clean. Let cool before serving.
- Prep Time: 20 mins
- Cook Time: 1 hour
- Category: Cake
- Cuisine: American
Nutrition
- Serving Size: 1 serving
- Calories: 430
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Frequently Asked Questions
Why does the rhubarb filling use cornstarch?
The rhubarb is tossed with 2 tsp of cornstarch (along with 1 tbsp orange zest, ¼ cup sugar, and scraped vanilla bean seeds) before being layered onto the batter. The cornstarch thickens the juices released during baking, helping the rhubarb set into jammy pockets rather than making the cake soggy.
What is the technique for the crumb topping, and how big should the pieces be?
The crumbs are made from a stiff dough of dark brown sugar, granulated sugar, cinnamon, salt, melted butter, and 1¾ cups cake flour. Step 5 instructs you to break it into big pieces with your fingers — about ½ to ¾ inch — before spreading over the top. Larger pieces stay chunky and crumbly after baking, which is the texture the article describes. 
Why is some of the cake batter held back before the rhubarb goes in?
Step 3 instructs you to separate out ½ cup of batter after mixing. In step 4, this reserved batter gets dolloped over the rhubarb layer before the crumb topping goes on. It creates an extra cushion between the fruit and the crunchy top, helping the cake stay moist inside.
