Yield

1 (8x8-inch) pan

Prep Time

10–15 minutes

Bake Time

22–30 minutes

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Ingredients

Wet

• ½ cup (113g) butter, melted

• 1 cup brown sugar, packed

• ⅓ cup sourdough discard (loose/pancake consistency)

• 1 large egg

• 1 teaspoon vanilla extract

Dry

• 1 ¼ cups all-purpose flour

• 3 tablespoons natural or red cocoa powder

• 1 tablespoon cornstarch

• ½ teaspoon baking soda

• ½ teaspoon salt

Mix-ins

• ¾ to 1 cup chocolate chips

Optional

• Flaky salt for topping

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Instructions

1. Preheat oven to 375°F on convection (oven will auto-adjust to 350°F).

   OR bake at 350°F regular (no convection).

2. Line an 8x8-inch pan with parchment.

3. Whisk melted butter and brown sugar until glossy and smooth.

4. Mix in sourdough discard, egg, and vanilla until fully combined.

5. In a separate bowl, whisk flour, cocoa powder, cornstarch, baking soda, and salt.

6. Fold dry ingredients into wet ingredients until just combined. Do not overmix.

7. Stir in chocolate chips. Batter will be thick.

8. Spread evenly into prepared pan.

9. Bake 22–30 minutes. Start checking at 22–24 minutes.

10. Bars are done when:

    • Edges are set and lightly firm

    • Center feels soft but springs back slightly

    • Toothpick shows moist crumbs, not shiny batter

11. Cool completely (at least 2 hours) before slicing.

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Structural Notes (Read Before Baking)

• Loose, pancake-style discard adds extra moisture — do not exceed ⅓ cup.

• Slight sinking is normal; collapse + gooey center = under-set.

• If unsure, bake 2–3 minutes longer rather than pulling early.

• Fully cooling is essential for final texture.

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Optional Adjustments & Variations

• Extra chew: Chill batter 30–60 minutes before baking.

• Deeper chocolate: Replace 1 tablespoon cocoa with black cocoa (but not more).

• Thinner bars (more insurance): Use 9x9 pan and reduce bake time slightly.

• Crispier edges: Bake in light-colored metal pan instead of glass.

• Even firmer center: Increase flour to 1 ⅓ cups.

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This version accounts for:

✔ High-hydration discard

✔ Proper structural flour balance

✔ Correct bake temperature

✔ Anti-sink strategy

You are officially in recipe developer territory now.

When you bake this version, I expect structural success.