STEP 1 — Brown the Butter

Place cut butter in a light-colored or stainless steel saucepan over medium heat. Let it melt completely. Once melted and bubbling, reduce heat to low. The butter will foam as the water cooks off — keep going. When golden-brown specks appear on the bottom and the aroma shifts to nutty and caramel-like, remove from heat immediately. Pour every last bit (including the browned specks) into a large heatproof bowl. Cool for about 30 minutes until barely warm to the touch.

⚠️ Watch Out: If the specks darken quickly, pull the pan off the heat immediately — residual heat will keep cooking it.

STEP 2 — Mix the Sugars Into the Brown Butter

Add both sugars to the cooled brown butter. Whisk vigorously until combined — the mixture will look like wet, grainy sand. This step helps dissolve the sugar slightly and contributes to a shinier, crinkled top on your finished cookie. (Stand mixer: paddle attachment, medium-low, 2 minutes.)

STEP 3 — Add Eggs, Vanilla & Discard

Add the whole egg and whisk until fully incorporated. Add the egg yolk and whisk again until glossy and smooth. Add the vanilla extract and whisk to combine. Finally, add the sourdough discard and whisk until the mixture is silky and uniform.

💡 Pro Tip: Check your discard's consistency here. If it pours easily like buttermilk, you may need an extra tablespoon or two of flour later.

STEP 4 — Add the Dry Ingredients

In a separate bowl, whisk together flour, baking soda, cornstarch, and salt. Add half the flour mixture to the wet ingredients and fold gently with a spatula until just combined. Add the remaining flour mixture and fold until no large pockets of dry flour remain — a few small streaks are fine. Do not overmix.

⚠️ Watch Out: Fold, don't whisk. The dough will look a little shaggy at first — keep folding and it will come together.

STEP 5 — Fold in the Chocolate

Add chopped chocolate or chips and fold until evenly distributed throughout the dough. The dough will be soft and slightly tacky — this is correct.

STEP 6 — Chill the Dough

Cover the bowl tightly with plastic wrap or a lid and refrigerate for at least 8 hours, up to 36 hours. Overnight is strongly recommended for best flavor and texture.

💡 Pro Tip: The longer the chill, the more pronounced the brown butter flavor becomes and the more complex the cookie. 24–36 hours is the sweet spot.

STEP 7 — Scoop and Shape

Remove dough from the fridge and let sit at room temperature for 1–2 hours until scoopable. Preheat oven to 350°F (176°C). Line two baking sheets with parchment paper. Scoop dough into balls of approximately 60g (about 2 tablespoons) each. Shape each ball slightly taller than it is wide — this encourages the cookie to spread up and out rather than going flat. Place 2 inches apart on prepared baking sheets. Sprinkle each ball with a small pinch of flaky sea salt.

STEP 8 — Bake

Bake for 15 minutes, rotating the pan halfway through. The cookies are done when the edges are golden and set but the centers still look slightly underdone and glossy. They will continue to cook on the hot pan after you remove them from the oven — do not wait for the centers to look fully set.

⚠️ Watch Out: Every oven runs differently. Start checking at 12 minutes if yours runs hot. Golden edges + crinkled, puffed top = ready.

STEP 9 — Cool