Fudgy Sourdough Discard Brownies

Name: Fudgy Sourdough Discard Brownies
Prep time: 25 min
Cook time: 28 min
Total time: 53 min
Yield: 16 servings
Cuisine: American
Ingredients: ½ cup (1 stick) (113 g) unsalted butter, cut into 1-inch pieces, plus a little extra for greasing the pan; ¾ cup (150 g) granulated sugar; ¼ cup, packed (55 g) light brown sugar, packed; ½ cup (45 g) unsweetened cocoa powder, sifted if lumpy; ½ tsp (3 g) fine salt; 2 large (100 g) large eggs, at room temperature; 2 tsp (10 ml) pure vanilla extract; ½ cup (120 g) unfed sourdough discard (100% hydration), stirred, cold or room temperature; ½ cup (60 g) all-purpose flour, spooned into the cup and leveled; ¼ tsp (1 g) baking soda; ⅔ cup (115 g) semisweet chocolate chips; ¼ tsp (1 g) flaky sea salt, for sprinkling on top (optional)

From the MyKitchenBank Kitchen

Dense, fudgy brownies with a crackly top and deep chocolate flavor. Unfed sourdough discard adds moisture and a subtle tang that makes the chocolate taste richer, without tasting sour.

Prep: 25 min
Cook: 28 min
Wait: 1 hr 5 min
Total: 1 hr 58 min
Makes: 16 brownies (one 8-inch square pan)

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Ingredients

16 servings

½ cup (1 stick) (113 g) unsalted butter, cut into 1-inch pieces, plus a little extra for greasing the pan
¾ cup (150 g) granulated sugar
¼ cup, packed (55 g) light brown sugar, packed
½ cup (45 g) unsweetened cocoa powder, sifted if lumpy
½ tsp (3 g) fine salt
2 large (100 g) large eggs, at room temperature
2 tsp (10 ml) pure vanilla extract
½ cup (120 g) unfed sourdough discard (100% hydration), stirred, cold or room temperature
½ cup (60 g) all-purpose flour, spooned into the cup and leveled
¼ tsp (1 g) baking soda
⅔ cup (115 g) semisweet chocolate chips
¼ tsp (1 g) flaky sea salt, for sprinkling on top (optional)

Equipment (8)

8×8-inch (20×20 cm) metal or light-colored baking pan
Parchment paper
Medium saucepan
Whisk
Silicone spatula
Measuring cups and spoons or a kitchen scale
Wire rack
Sharp chef's knife

Steps

Before you start

Use unfed discard straight from the fridge or at room temperature. It should be roughly 100% hydration (equal weights flour and water), like a thick pancake batter. Stir it before measuring.
Weigh the ingredients if you can. Brownies are sensitive to too much flour, and a scale keeps them fudgy.
Position an oven rack in the center and preheat to 350°F (175°C) before you start mixing.
Plan for at least 1 hour of cooling. Cutting warm brownies gives messy, gooey squares.

1
Prepare the panOven 350°F / 175°C
- Position a rack in the center of the oven and preheat to 350°F (175°C).
- Lightly butter an 8×8-inch (20×20 cm) pan.
- Line it with parchment so two sides hang over as handles, then lightly butter the parchment.
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Ready when: Pan is lined with a parchment sling and the oven is fully preheated.
Tip: A sling lets you lift the whole slab out for clean cuts.
2
Melt butter and sugars
- In a medium saucepan over low heat, melt the butter, stirring occasionally, until fully liquid with no solid pieces left, about 3 minutes.
- Remove from the heat and whisk in the granulated sugar and brown sugar for 30 seconds until the mixture looks like wet sand.
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Ready when: Butter is completely melted and the sugars are evenly mixed in.
Tip: Don't let the butter brown or sizzle; it should only melt.
3
Whisk in cocoa
- Add the cocoa powder and salt to the warm butter mixture.
- Whisk for about 1 minute until smooth, thick, and no dry streaks remain.
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Ready when: Mixture is glossy, thick, and free of cocoa lumps.
Tip: Sift the cocoa first if it's clumpy, since lumps are hard to whisk out later.
4
Cool the chocolate base
- Let the saucepan sit on the counter for 5 minutes, stirring once halfway through.
- The mixture should be warm, not hot.
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Ready when: The side of the pan feels warm but comfortable to touch.
Tip: Adding eggs to a hot mixture can cook them into flecks.
5
Beat in eggs
- Add the eggs and vanilla to the saucepan.
- Whisk vigorously for 1 full minute until the batter turns glossy, thick, and slightly lighter in color.
- This builds the shiny, crackly top.
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Ready when: Batter is shiny and smooth and falls from the whisk in a thick ribbon.
6
Stir in discard
- Add the sourdough discard and whisk for about 30 seconds until fully blended and no streaks of starter remain.
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Ready when: Batter is uniformly dark brown with no pale streaks.
7
Fold in dry ingredients
- Sprinkle the flour and baking soda over the batter.
- Switch to a spatula and fold gently until just a few flour streaks remain.
- Add ⅔ of the chocolate chips (about ½ cup / 75 g) and fold until the flour disappears.
- Stop mixing right away.
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Ready when: No dry flour is visible and the batter is thick and fudgy.
Tip: Overmixing develops gluten and makes brownies cakey and tough.
8
Fill the pan
- Scrape the batter into the prepared pan and spread it into an even layer, pushing it into the corners.
- Scatter the remaining chocolate chips (about 40 g) over the top.
- Sprinkle with flaky salt, if using.
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Ready when: Batter is level, about ¾ inch (2 cm) deep.
9
Bake the browniesOven 350°F / 175°C
- Bake at 350°F (175°C) for 26 to 30 minutes.
- The edges should look set and slightly pulled from the pan, and the top should be shiny with fine cracks.
- A toothpick inserted 2 inches from the edge should come out with a few moist crumbs, not wet batter.
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Ready when: Edges are set, top is crackly, and a toothpick comes out with a few moist crumbs. The center reaches about 200°F (93°C).
Tip: Check at 26 minutes. Overbaking turns fudgy brownies dry.
10
Cool completely
- Set the pan on a wire rack and cool for at least 1 hour at room temperature.
- The brownies will finish setting as they cool.
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Ready when: The pan is no longer warm and the center feels firm when pressed lightly.
Tip: For very neat squares, chill the cooled pan for 30 minutes before cutting.
11
Slice and serve
- Lift the brownie slab out using the parchment handles.
- Cut into a 4×4 grid to make 16 squares with a sharp knife, wiping the blade clean between cuts.
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Ready when: Squares have clean edges and a fudgy center.
Tip: Wipe the knife with a damp towel after each cut for the cleanest edges.

Good to know

Tips

Whisking the eggs into the warm chocolate mixture for a full minute is what creates the shiny, crackly top.
Use a light-colored metal pan. Dark pans and glass can over-brown the edges before the center is set.
The baking soda neutralizes the acid in the discard. Don't skip it, or the brownies may taste sour.
Very old or gray-liquid discard can taste sharper. Stir the liquid in and use discard that is under 2 weeks old for the best flavor.

Make ahead

"Bake the brownies up to 2 days ahead and store them uncut in the pan, covered tightly, at room temperature. Slice just before serving. The flavor deepens overnight."

Storage & reheating

"Room temperature: airtight container, up to 3 days. Refrigerator: up to 1 week; bring to room temperature or warm 10 seconds in the microwave before serving. Freezer: wrap squares individually and freeze up to 3 months; thaw at room temperature for 1 hour or microwave 15 to 20 seconds."

Substitutions

all-purpose flour → 1:1 gluten-free baking flour blend. Works well; the brownies may be slightly more fragile, so cool completely before cutting.
semisweet chocolate chips → chopped dark chocolate or walnuts. Use the same weight. Chopped chocolate gives more melty pockets.
unsalted butter → refined coconut oil or neutral oil. Use 100 g oil for 113 g butter; the brownies will be slightly less rich in flavor.
unfed sourdough discard (100% hydration) → active, fed starter. Works at the same weight, but the batter may rise a little more and taste slightly tangier.