A soft and spongy sweet cake, speckled with bites of tart, magenta rhubarb, and topped with a crunchy, cinnamon-sugar topping. Sourdough Rhubarb Cake is moist and the perfect recipe to use up any extra starter you have in the fridge. Serve it as breakfast, an afternoon pick-me-up, or as an evening dessert.
Rhubarb season is in full bloom here in the midwest and I’m not complaining! I have always been a fan of the wonderful flavor of tart rhubarb and gobble up all of the rhubarb recipes I can find. I am not a fan of overly sweet treats, so adding tart rhubarb to this sweet vanilla cake brings perfect balance. Plus, when you see deep magentas and rosey reds popping through cakes or crumbles – it’s stunning!
When my mother-in-law begged me to take some rhubarb home before her rhubarb plants gets out of control, I happily obliged. On top of that, she shared with me a new rhubarb recipe, but knowing me, I had to give it a sourdough twist.
I love adding sourdough discard to cake recipes because it makes for the most fluffy and tender crumb! Why? Because of the acidity from the fermented discard! Adding any acid to a cake batter, like lemon juice, buttermilk, or discard, slows down the formation of gluten. Too much gluten equals a tough cake. But when you add sourdough discard, it gives you light, airy bites of cake – delicious!
Once baked in the oven, the slices of crunchy rhubarb turn jammy. Plus, the sugar and cinnamon topping creates this delicate crust on top of the cake. So simple, but the combination of rhubarb and hints of vanilla and cinnamon beautifully complement each other. My cake tester, aka my husband, has been loving his job with this delicious recipe!
I highly encourage you to serve this cake warm. A dollop of homemade whipped cream or vanilla ice cream wouldn’t hurt either. Sourdough Rhubarb Cake is a simple summertime sweet treat that you can enjoy again and again.
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Why You’ll Love This Recipe:
Sweet & Tart:
Each bite is met with a sweet, vanilla cake and bits of jammy, tart rhubarb, which is then finished off with a simple crunch cinnamon and sugar topping. No frills or fuss, but just a delicious sweet and tart cake.
Super Moist:
Sourdough discard is quite acidic due to the fermentation and when you add it to any baked it, it slows down the formation of gluten. What does this mean for you? The lightest and most moist cake! The acidity of the discard also reacts with the baking soda, helping it to rise to great heights for an airy crumb. Talk about yum!
Easy Recipe:
This great recipe is basically a dump, mix, and bake kind of recipe. No extra devices or confusing steps, just mix the batter in a stand mixer and pop it in the oven. Recipes like this one are perfect to have on hand because they are quick to make but sure to impress!
Great way to use up sourdough discard:
I’m always on the hunt for new recipes to add my sourdough discard into. From blueberry lemon poppy seed muffins to blueberry buckle to banana bars, and now rhubarb cake, adding sourdough discard not only gives a slightly tangy flavor that I love but it makes for the lightest and most airy crumbs. It’s the perfect way to use up that discard.
Ingredients:
Batter:
Sugar
White Sugar
Egg
Vanilla Extract
Milk
Sourdough Starter
All-Purpose Flour
Baking Soda
Fresh Rhubarb
Crumb Topping:
Sugar
Cinnamon
Supplies
Stand Mixer or Hand Mixer
Measuring Cup
Baking Dish or Cake Pan
How to Make Sourdough Rhubarb Cake:
Preheat oven to 350 degrees f.
Either grease or line a 9×13 baking dish with parchment paper. This is optional, but I love how easily removing the cake is with parchment paper. I can lift it and cut the cake into even squares perfectly, but you choose.
Chop rhubarb into 1/2-inch pieces, bite-sized. Place them in a small bowl and set them to the side.
Whisk the discard, milk, and vanilla in a small bowl until combined. Set to the side.
In a bowl of a stand mixer with a paddle attachment cream the butter and sugar for about 2 minutes.
Add the egg to the sugar mixture and beat until fluffy with a pale yellow color, for about 3 minutes.
In a medium bowl, whisk together the flour and baking soda.
Alternate adding the dry ingredients and wet ingredients. Add about a third of the flour mixture, then half of the liquids. Repeat until all of the ingredients have been added and the flour bits have just disappeared. (Note that the batter is on the thicker side)
Be sure to not overmix the cake batter – this can lead to a tough crumb.
Lastly, fold in the bits of rhubarb.
Pour the batter into the baking dish. You can even top it with more pieces of rhubarb if that wasn’t enough rhubarb for yeah!
In a separate bowl, mix together the sugar and cinnamon. Sprinkle on top of the batter – make sure to get all the edges of the cake. Bake in the oven for 40-45 minutes or until a toothpick comes out clean.
Let the cake cool on a wire rack before slicing and enjoy!
How to Serve Sourdough Rhubarb Cake
A slice of warm Sourdough Rhubarb Cake is perfectly delectable on its own, but a fresh sprinkle of powdered sugar, a dollop of homemade whipped cream and fresh fruit, or a scoop of vanilla ice cream will surely take it up a notch.
How to Store Sourdough Rhubarb Cake
Store any leftover cake in an airtight container at room temperature for up to 3 days.
It also freezes really well! Wrap slices of cooled cake with plastic wrap and store in a ziplock bag for up to 3 months. Thaw on the countertop until room temperature.
FAQs:
What kind of sourdough starter should I use for Sourdough Rhubarb Cake?
Use sourdough discard, or unfed sourdough starter, to make this delicious cake. Don’t worry, the sweetness from the cake masks any tanginess from the discard and you are left with a moist and airy cake.
Can I use frozen rhubarb?
Absolutely! No need to thaw the rhubarb, just fold in the frozen slices of rhubarb just before baking.
When is rhubarb season?
Rhubarb season in most areas is from April to June. It is one of the first veggies of the season and it is quite bountiful!
Happy baking!
More Sourdough Discard Recipes:
Strawberry Rhubarb Pie with a Sourdough Crust
Sourdough Discard Blueberry Buckle
Blueberry Lemon Poppy Seed Sourdough Muffins
Moist Sourdough Rhubarb Cake Recipe
Yield: 16 slices
Prep Time: 20 minutes
Cook Time: 40 minutes
Total Time: 1 hour
A soft and spongy sweet cake, speckled with bites of tart, magenta rhubarb, and topped with a crunchy, cinnamon-sugar topping. Sourdough Rhubarb Cake is moist and the perfect recipe to use up any extra starter you have in the fridge. Serve it as breakfast, an afternoon pick-me-up, or as an evening dessert.
Ingredients
Cake Batter
- 2 cups of chopped rhubarb, 1/2 inch slices
- 1/2 cup milk (125ml)
- 1 cup unfed sourdough starter (285g)
- 1 tsp vanilla extract
- 1/2 cup of butter, softened
- 1 1/2 cups sugar (350g)
- 1 large egg
- 1 1/2 cups flour, spooned and sifted (150g)
- 1 tsp baking soda
Topping
- 1/4 cup sugar
- 1/2 tsp ground cinnamon
Instructions
How to Make Sourdough Rhubarb Cake:
Preheat oven to 350 degrees f.
Either grease or line a 9x13 baking dish with parchment paper. This is optional, but I love how easily removing the cake is with parchment paper. I can lift it and cut the cake into even squares perfectly, but you choose.
Chop rhubarb into 1/2-inch pieces, bite-sized. Place them in a small bowl and set them to the side.
Whisk the milk, vanilla, and sourdough discard in a small bowl until combined. Set to the side.
Mix
In a bowl of a stand mixer with a paddle attachment, cream the butter and sugar for about 2 minutes.
Add the egg to the sugar mixture and beat until fluffy with a pale yellow color, for about 3 minutes.
Dry Ingredients
In a medium bowl, whisk together the flour and baking soda.
Alternate adding the dry ingredients and wet ingredients. Add about a third of the flour mixture, then half of the liquids. Repeat until all of the ingredients have been added and the flour bits have just disappeared. (Note that the batter is on the thicker side)
Be sure to not overmix the cake batter - this can lead to a tough crumb.
Lastly, fold in the bits of rhubarb.
Bake
Pour the batter into the baking dish. You can even top it with more pieces of rhubarb if that wasn't enough rhubarb for yeah!
In a separate bowl, mix together the sugar and cinnamon. Sprinkle on top of the batter - make sure to get all the edges of the cake. Bake in the oven for 40-45 minutes or until a toothpick comes out clean.
Let the cake cool on a wire rack before slicing and enjoy!
Notes
What kind of sourdough starter should I use for Sourdough Rhubarb Cake?
Use sourdough discard, or unfed sourdough starter, to make this delicious cake. Don't worry, the sweetness from the cake masks any tanginess from the discard and you are left with a moist and airy cake.
Can I use frozen rhubarb?
Absolutely! No need to thaw the rhubarb, just fold in the frozen slices of rhubarb just before baking.
Did you make this recipe?
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