Fudgy, ultra-rich, and with a dark chocolatey flavour, these sourdough brownies are an excellent way to use up some of that extra sourdough discard.

Fudgy Sourdough Brownies
Really very fudgy – these are almost like eating a dark chocolate bar. If you like a deep dark chocolate brownie, this recipe is for you! Sourdough discard is added to the mix because we always have extra, and it adds the slightest touch of sourdough flavour.
Though it might seem a bit strange and unnecessary to add sourdough to brownies, we’re all about reducing food waste. Instead of tossing your discard on the compost heap, add it to baking – and that doesn’t only mean bread. We have a number of sourdough discard recipes and it’s being added to all the time. You can make sourdough banana bread, sourdough crepes, sourdough cookies, and, obviously, sourdough brownies!
The taste of any of these treats, including the brownies, isn’t strongly of sourdough in the same way as a proper sourdough bread because they’re not going through a bulk ferment. There’s a bit of tang here, but it’s only just noticeable.
Ingredients
- Butter
- Cane sugar
- Brown sugar
- Vanilla
- Cocoa powder (see below)
- Salt
- Two eggs
- Sourdough starter discard
Method
Preheat the oven and line a standard square baking tin (a rectangle will work too, just keep it around the same size as a 20cm (8 in.) tin). Lining instead of greasing is key here because brownies don’t pop out of the pan like a cake does, so you’d scratch your tin.
Butter, sugars, vanilla, cocoa, and salt are whisked together to mix out all the lumps. The batter is very stiff at this point, so you’ll need a strong whisk, or switch over to a wooden spoon. Whisk in the eggs to combine, and lastly the sourdough discard. Depending on the cocoa you’ve used, your batter might be very dark, almost black.
Pour/spoon the batter into the tin – it might be too thick to pour – and smooth out the top. Bake for 20-25 minutes (don’t over-bake – see below) and cool completely before cutting and serving the brownies.
Serve with some ice cream, or whipped cream, berries, fudge sauce, caramel, whatever you like. I (Alex) like storing the brownies in the fridge for a really fudgy, chewy bite, but they’re great at room temperature too. These remind me of those little brownie bites you get at the grocery store bakery.
Substitutions
Since this is such a minimal recipe, there aren’t a pile of substitutions to offer. You can easily make these dairy-free by using a good quality vegan butter (as pictured because Alex doesn’t eat dairy) but we don’t have a good sub for eggs to make them fully vegan. Izy has a vegan sourdough brownie recipe that looks great!
We use regular cocoa powder, but you can also use Dutch process here because there isn’t a leavening agent needed. If you like a lighter coloured, but less sweet, brownie, you can use raw cacao powder. Don’t mix up cocoa with hot cocoa drink mix – check the ingredients if you’re not sure, as the drink mix has sugar and other ingredients added.
Making These Gluten Free
The base recipe here is completely gluten free. So if you have a gluten free sourdough starter, you can use discard from that in place of a wheat based starter. That recipe linked above is great, and if you’d like to delve more into GF sourdough, this book includes a number of excellent recipes and we can highly recommend it.
Tips and Notes
The recipe calls for the brownies to be cooled fully in the pan before cutting. This is because the edges will be messy if you cut while they’re still warm, but if you’re craving warm brownies, it’s okay to cut them before fully cooling. Or, you know, dive right in with a spoon.
Don’t worry about over-mixing here as the brownies are gluten-free apart from the discard. It is a stiff dough and needs to be mixed well.
Really, really, don’t over bake! It’s a short baking time, yes, but that’s what you need for that fudge-like interior. A toothpick test will fail so go by the baking time instead – when they’re done, the edges will be raised and firm to the touch.
We left out additional chopped chocolate because the brownies are so rich, but you could add some dark, milk, or white chocolate to the mix. Add it with the dry ingredients because it’ll be hard to incorporate once the batter is fully mixed. Or add chopped nuts, coconut flakes, berries, whatever you like.
More Brownie Recipes
Double Chocolate Buckwheat Brownies (GF)
Black Bean Fudge Brownies (V, GF)
Spelt Almond Butter Brownies (V)
Almond Flour Brownies (GF, DF)
If you make this recipe, let us know by tagging @baked_theblog + #bakedtheblog on Instagram! We love to feel like we’re in the kitchen with you.
Recipe
Sourdough Brownies
Description
Equipment
- Measuring cups and spoons or a digital kitchen scale
- 8 x 8-inch (20 x 20 cm) baking pan
- Parchment paper
- Whisk
- Spatula
- Mixing bowl
Ingredients
- ½ cup butter, melted and slightly cooled
- ¾ cup cane sugar
- ½ cup brown sugar, packed, if using cups
- 1 teaspoon vanilla extract
- ¾ cup cocoa powder
- ½ teaspoon fine sea salt
- 2 large eggs, at room temperature
- ⅓ cup sourdough starter, unfed
Instructions
- Preheat oven to 350°F (180°C) and line an 8 x 8-inch (20 x 20 cm) baking pan with parchment paper.
- In a large bowl, whisk together the butter, cane sugar, brown sugar, vanilla extract, cocoa powder (no need to sift, you’ll whisk out the lumps), and salt. The batter will be quite stiff, but will loosen up as you add the remaining ingredients.
- Next, whisk in the eggs until combined.
- Finally, add the sourdough starter and mix until smooth.
- Transfer batter into the prepared baking pan and smooth out the surface as best as possible.
- Bake 20 to 25 minutes, or until edges have formed and the center is just set. Don’t be tempted to over-bake; the brownies will set more as they cool.
- Cool completely in the pan before cutting and serving.
Ceecee says
These brownies were amazing!! I was looking for a simple sourdough brownie recipe that used cocoa powder and basic ingredients and this hit the spot. I only had a 9×5 pan so i halved the recipe and they came out perfect. Great way to use sourdough discards, im going to be using this recipe often! Thank you!
Traci L Deblieck says
So I just baked these and it was an absolute disaster. I baked them for 25 minutes and although the edges were firm and the top of the center was set, when I cooled and cut them, they were no firmer than the original batter was and did not hold their form at all. They were so sticky that they were inseparable from the parchment paper or each other. The flavor was good but it all had to be thrown out. Any idea what went wrong here please? Thank You
Alexandra Daum says
Hi Traci, so sorry to hear you had some trouble with the brownies. Can you give us any information about any changes you might have made, baking temperature, altitude, anything like that? It’ll help us to troubleshoot.
Scott says
I had the same experience. I’d strongly recommend not removing the brownies from the oven until an inserted wooden skewer coming out clean of batter.
Dana says
These turned out great and the recipe proved adaptable. I was seeking a recipe that would use cocoa instead of baking chocolate-thanks! I used 100g of discard starter, and from the pictures, my starter seems to be a little thicker. I also cut the cocoa (used special dark) to 2/3 cup and it was still perfectly dark. I think this also allowed me to successfully reduce the sweetener. I used 2/3 c brown sugar and 1/3 cup monkfruit for baking. I also subbed coconut oil for half of the butter. I added a scant 1/4t of baking powder out of instinct. 23 minutes was just right-toothpick comes out not quite clean. The texture is perfect! I will definitely make again and load them up with some fun extras-nuts, coconut, white chocolate, etc.
Lory says
These were delicious – thank you so much! Such a great way to use up starter, which I can’t bring myself to discard. My family LOVED them and ate them all up with ice cream. I’ve just made another batch today but substituted the butter for vegetable oil (just because I’d run out of butter) and they are just as yummy (and also terrible for the waistline). Some people may not like them because if you are using starter discard the live bacteria in the yeast will not be very active, therefore the centre doesn’t really bake – don’t expect fluffy crumbs, this is way more like a fudgy pudding/mouse thing.
Debbie says
These brownies were delicious and not at all “wet” in the center. I used Special Dark 100% Cacao cocoa powder. I substituted 12 packets of organic stevia for the cane sugar and 1/4 cup of organic coconut oil in place of half the butter. I used an 8×8 pan per instructions and baked the brownies at 350 degrees for exactly 25 minutes. I cut the brownies about 3 hours after baking and served with a homemade whipped cream topping. Dark chocolate fudgy and delicious!
Mare Simone says
Best brownie recipe ever. Love the rich fudge texture. Exactly what I was looking for to use some starter and cocoa powder, I used half butter and half coconut oil brown sugar and turbine sugar, they came out so totally wonderful. I baked them for 20 minutes they were very moist in the middle so I put them in for another 5 and tho still moist in the middle when they cooled, they were perfect.
Regina says
Very delicious. They took nearly 15 additional minutes to bake than stated. Best Sourdough brownie recipe I have come cross. I have baked several different ones. I like that it has cocoa powder and I can skip the step to melt chocolate.
EJC says
Holy moley! I made a double batch and once I tested them, I was so glad I did! These are so moist and fudgy!
AriesWolf says
Holy crap, these were amazing!!! They ended up being my platonic ideal of a fudgy brownie.
My sourdough starter is 50/50 rye and whole wheat. It worked beautifully. I also added in about a cup of chocolate chips.
I baked these in a metal 8 x 8 tin. I didn’t have any parchment paper, so I just sprayed the pan with nonstick spray, and I had no trouble getting the brownies out.
I’ll definitely be making these again. If there’s a better use for sourdough discard, I haven’t found it!