Sourdough Discard Rhubarb Cake
This tender sourdough discard rhubarb cake is the perfect way to use up your extra starter, delivering a beautifully moist crumb with a tangy-sweet rhubarb topping that tastes like it came straight from a countryside bakery.
The Sourdough Discard Rhubarb Cake You Will Bake on Repeat
If you have a jar of sourdough discard sitting in your fridge and a bundle of rhubarb on your counter, you are minutes away from one of the most satisfying bakes of the season. This sourdough discard rhubarb cake is soft, buttery, and deeply flavored, with jewel-bright pieces of rhubarb baked right into the top and a warm cinnamon-sugar crust that crackles just slightly as it cools. It is the kind of cake that belongs on an Easter breakfast table, a Sunday afternoon spread, or simply next to a strong cup of tea on a grey morning.
This recipe sits at a beautiful crossroads of sourdough discard recipes sweet and classic English baked goods. Think of it as a rhubarb traybake with a bakery-worthy crumb, the kind of thing you would find wrapped in parchment at a farmhouse kitchen counter.
Why Sourdough Discard Makes This Cake Special
If you have been looking for different sourdough recipes beyond bread, this cake is your answer. Sourdough discard brings three things to a bake that you simply cannot fake:
- Moisture: The fermented starter keeps the crumb incredibly tender for days.
- Tang: A gentle, subtle sourness that makes the sweetness feel more complex and less one-dimensional.
- Depth: That hard-to-name quality that makes people say, "What is in this?" and reach for a second slice.
It is not a strong sourdough flavor at all. It is background richness, the kind that elevates a simple rhubarb cake into something that tastes genuinely considered.
Chef's Tip: Use discard that is anywhere from a few days to a week old straight from the fridge. You do not need to feed or activate it. Room temperature discard blends more smoothly into the batter, so set it out 30 minutes before you start.
Choosing the Right Rhubarb
Fresh, firm rhubarb stalks are ideal here. Look for stalks that are bright pink to red with no limpness or browning. The pinker the stalks, the more visually striking your cake will be. That said, green rhubarb tastes just as good, it simply produces a more muted color on top.
Cut the rhubarb into roughly half-inch pieces. Smaller pieces will melt into the cake and disappear, while larger chunks can make the top soggy. Half-inch is the sweet spot for distinct pockets of tender, jammy rhubarb in every bite.
The Tools and Ingredients That Actually Matter Here
For sourdough discard pastry recipes and cakes like this one, the quality of your butter and the accuracy of your pan size genuinely affect the final result. An 8x8 inch pan gives you the perfect depth for a moist crumb and a caramelized top.
Tips for a Perfect Bake Every Time
This is a forgiving recipe, but a few habits will make the difference between good and bakery-level good:
- Do not overmix once the flour goes in. Fold gently until just combined.
- Room temperature ingredients are non-negotiable. Cold butter will not cream properly, and cold eggs can cause the batter to split.
- Press the rhubarb in lightly so it sits half-embedded in the batter rather than resting purely on the surface.
- The cinnamon sugar topping is optional but strongly encouraged. It creates a faintly crisp, caramelized layer over the rhubarb that makes this feel like a proper bakery food recipe.
If you are planning this as one of your Easter breakfast pastries or a make-ahead treat for guests, good news: this cake is even better on day two. The crumb tightens just slightly overnight and the rhubarb flavor deepens throughout the whole cake.
Storage Tip: Wrap the cooled cake tightly or store it in an airtight container. It keeps beautifully on the counter for two days and in the fridge for five.
Ready to bake? Here is everything you need:
Sourdough Discard Rhubarb Cake
This tender sourdough discard rhubarb cake is the perfect way to use up your extra starter, delivering a beautifully moist crumb with a tangy-sweet rhubarb topping that tastes like it came straight from a countryside bakery.
Ingredients
- 1 1/2 cups all-purpose flour, spooned and leveled
- 1 1/2 tsp baking powder
- 1/4 tsp baking soda
- 1/2 tsp fine sea salt
- 1/2 cups unsalted butter, softened to room temperature
- 3/4 cups granulated sugar
- 2 large eggs, room temperature
- 1/2 cups sourdough discard, unfed, at room temperature
- 1/4 cups sour cream or full-fat yogurt
- 1 tsp pure vanilla extract
- 2 cups fresh rhubarb, trimmed and cut into 0.5-inch pieces
- 2 tbsp granulated sugar, for topping
- 1/2 tsp ground cinnamon, for topping
Instruction
Preheat your oven to 350 degrees F (175 degrees C). Grease an 8x8 inch square baking pan and line it with parchment paper, leaving an overhang on two sides for easy lifting.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the softened butter and sugar together with an electric hand mixer on medium-high speed for 3 to 4 minutes, until the mixture is pale, light, and fluffy.
Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed.
Add the sourdough discard, sour cream, and vanilla extract to the butter mixture. Mix on low speed until just combined. The batter may look slightly curdled at this stage and that is completely normal.
Add the dry ingredients to the wet ingredients and fold gently with a rubber spatula until no dry streaks remain. Do not overmix.
Pour and spread the batter evenly into the prepared pan.
Scatter the chopped rhubarb pieces evenly over the top of the batter, pressing them in very lightly.
In a small bowl, stir together the 2 tablespoons of sugar and cinnamon. Sprinkle this mixture evenly over the rhubarb.
Bake for 40 to 47 minutes, or until the top is golden, the edges have pulled away from the pan slightly, and a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for at least 20 minutes before lifting out using the parchment overhang. Slice into 9 squares and serve warm or at room temperature.
Equipment
- 8x8 inch square baking pan
- Parchment paper
- Large mixing bowl
- Medium mixing bowl
- Electric hand mixer or stand mixer
- Rubber spatula
- Whisk
- Small bowl
Notes
How to Serve This Cake
This is a sweet sourdough loaf recipe spirit in traybake form, which means it is casual enough to eat plain and special enough to dress up. A few ideas:
- Serve warm with a generous spoonful of clotted cream or crème fraîche
- Dust with powdered sugar just before serving for a pretty finish
- Pair with a scoop of vanilla bean ice cream for a proper quick discard dessert
- Serve in slim slices alongside other Easter breakfast pastries on a brunch board
However you slice it, this sourdough discard rhubarb cake is the kind of bake that makes your whole kitchen smell incredible and disappears faster than you expect. Save the recipe now, because you will be coming back to it all rhubarb season long.
