Fudgy Sourdough Discard Brownies

Last Tuesday, I was staring at a jar of sourdough discard, wondering if I could finally stop feeling guilty about tossing it out, when my friend texted asking me to bring dessert to dinner. Something about the tangy, slightly funky smell of that starter made me think—why not fold it into brownies? The result was richer and more complex than I expected, with a subtle depth that no regular brownie had ever given me. Now I make these constantly, and everyone asks what my secret is.

I brought these to a dinner party during a snowstorm, and someone ate three pieces before realizing they were made with sourdough starter. The disbelief in their eyes was priceless—they expected something weird or sour, but instead found themselves biting into pure fudgy bliss. That's the moment I knew this recipe needed to become a regular in my kitchen.

Ingredients

• Dark chocolate (170 g, 60–70% cocoa), chopped: This is where the magic starts—use good chocolate here because you're tasting every note of it, and mid-range chocolate will show up immediately.
• Unsalted butter (115 g) and neutral oil (60 ml): The butter brings richness while the oil keeps the crumb tender and fudgy instead of cakey, a trick I learned after making dense hockey pucks my first few tries.
• Granulated sugar (200 g) and light brown sugar (100 g, packed): The combination of both sugars creates depth and moisture that makes these brownies stay soft in the center, brown sugar adds caramel undertones that round everything out.
• Eggs (2 large) and egg yolk (1): Room temperature eggs emulsify better, creating that luxurious fudgy texture—cold eggs will fight you here.
• Sourdough discard (120 g, unfed and at room temperature): This is the secret ingredient that adds complexity and keeps brownies moist longer than normal, the unfed starter works best because you want that slight tang without aggressive fermentation.
• Pure vanilla extract (1 tsp): Vanilla bridges the gap between the chocolate and sourdough, making them feel like they belong together.
• All-purpose flour (60 g) and Dutch-process cocoa powder (35 g): Dutch-process cocoa gives deeper, earthier notes than natural cocoa, and keeping flour low is the entire reason these stay fudgy.
• Fine sea salt (½ tsp) and flaky sea salt (topping): Fine salt in the batter dissolves and balances sweetness, flaky salt on top gives you little bursts of minerality that make your brain light up.

Instructions

Heat and melt:

Preheat your oven to 175°C (350°F) and line that 20x20 cm pan with parchment, leaving overhang on two sides—this is your brownie escape route. Set a heatproof bowl over simmering water and let the chocolate and butter get to know each other, stirring until completely smooth, then whisk in the oil and remove from heat.

Build the base:

Whisk those sugars into the warm chocolate mixture until everything looks glossy and almost fluffy—this takes about a minute and your arm will know when it's right. You're creating the foundation that keeps these brownies fudgy, so don't rush this step.

Add the eggs:

Crack in one egg, whisk like your life depends on it for 30 seconds, then repeat with the second egg and finally that yolk—each addition needs a proper whisking so everything emulsifies. After the last egg goes in, keep whisking vigorously for 1–2 minutes until the mixture looks thick and shiny, almost mousse-like.

Stir in the sourdough magic:

Pour in that sourdough discard and vanilla, stirring until there are no white streaks of starter visible and everything feels integrated. This is where the tanginess enters the party quietly, ready to enhance everything chocolate.

Fold in dry ingredients:

Sift the flour, cocoa powder, and fine sea salt directly over the batter, then fold gently with a spatula using as few strokes as possible—overmixing develops gluten and turns fudgy brownies into cakey ones, the enemy. Stop folding the second you don't see dry flour anymore.

Pan and top:

Pour the batter into your prepared pan and smooth it out with a spatula, then sprinkle that flaky sea salt generously across the surface—be generous, the salt melts slightly during baking and creates this perfect contrast. The sparkle also tells you these aren't ordinary brownies.

Bake with patience:

Slide into the oven for 28–32 minutes, watching for the moment when the edges look set but the center still jiggles slightly when you give the pan a gentle shake—a toothpick should come out with moist crumbs, not clean. This is the hardest part because your kitchen will smell incredible and you'll want to eat them immediately.

Cool completely:

Let them cool in the pan on a wire rack until room temperature, then lift out using that parchment overhang and slice into 16 squares with a sharp knife wiped clean between cuts. This patience pays off because warm brownies crumble, but room temperature ones slice beautifully.

Pin This

A few weeks ago, my neighbor knocked on my door asking if I had made brownies the night before because she could smell them from her house. That's when I realized these weren't just a way to use up discard anymore—they'd become the dessert that makes people stop mid-conversation and close their eyes for a moment.

The Sourdough Secret

Using sourdough discard in baking isn't new, but most recipes use it in bread or pancakes where the tang gets lost in the rest of the flavor. In brownies, it becomes this quiet sophistication that lives underneath the chocolate, making each bite feel a little more complex than it should. The acidity also interacts with baking soda would do in regular recipes, creating better rise and a slightly lighter crumb than you'd expect from such a dense-looking batter.

Why This Works

The oil-to-butter ratio is what separates these from dry, dense brownies that disappoint. Oil adds moisture and keeps the brownies tender even after a few days of sitting around, while butter provides structure so they don't fall apart completely. The sourdough discard adds moisture too, which means you can use less flour than most brownie recipes and still have enough structure to slice cleanly.

Storage and Serving Ideas

These brownies improve slightly after a day or two as flavors meld together, so if you can resist eating them all immediately, wait until tomorrow for the best version. Room temperature storage in an airtight container keeps them perfect for up to three days, and freezing works beautifully if you want them on hand for unexpected guests or moments of weakness.

• Pair with espresso in the morning or a glass of red wine after dinner—both bring out the chocolate in different ways.
• Add 100 g of chopped dark chocolate or chocolate chips folded in before baking if you want extra decadence and chewy pockets throughout.
• A light dusting of fleur de sel on top of each slice just before serving makes them feel like a restaurant dessert.

Pin This

These brownies have become my favorite way to rescue sourdough discard and impress anyone I'm cooking for, because nothing says thoughtfulness like a dessert that tastes like a secret. Bake them once and you'll understand why I make these constantly.

Recipe FAQ

→ Why use sourdough discard in these brownies?

Sourdough discard adds a subtle tang and moist texture, enhancing the depth of flavor without overpowering the chocolate.

→ How can I tell when the brownies are done baking?

The edges should be set while the center remains slightly soft; a toothpick inserted should come out with moist crumbs.

→ Can I add extra chocolate to the batter?

Yes, folding in chopped dark chocolate or chips before baking increases richness and texture.

→ What is the role of flaky sea salt on top?

Flaky sea salt enhances the sweet flavor by adding a delicate salty crunch, balancing the richness.

→ How should I store these brownies to maintain freshness?

Store airtight at room temperature for up to 3 days or freeze for longer storage without losing moisture.