Sourdough Discard Chocolate Chip Cookies

Before you start

Sourdough discard does two jobs in these cookies. Its water hydrates the flour so the dough bakes up chewy and bendy instead of cakey, and its fermented flavor adds a subtle tang that plays well against brown sugar and dark chocolate. Because discard supplies liquid, the recipe uses a single egg yolk rather than a whole egg; adding both would make the dough slack and the cookies spread.

Chilling is not optional. An hour firms the butter so the cookies hold their shape, and a longer rest of up to three days lets enzymes in the dough break down starch into sugars, which gives deeper browning and more toffee flavor. Bake until the edges are set but the centers still look slightly underdone.

Ingredients

• 170 g (¾ cup) unsalted butter — softened to about 18°C (65°F)
• 150 g (¾ cup packed) dark or light brown sugar
• 50 g (¼ cup) granulated sugar
• 100 g (scant ½ cup) sourdough discard (100% hydration) — unfed
• 1 large (about 18 g) egg yolk
• 2 tsp vanilla extract
• 250 g (2 cups + 1 tbsp) all-purpose flour
• 1 tsp baking soda
• 1 tsp fine salt
• 225 g (about 1⅓ cups chopped) dark chocolate — chopped into chunks
• as needed flaky salt — for the tops; optional

Method

1. Beat the butter and both sugars on medium speed for 2 minutes, until creamy and slightly lighter.
2. Add the discard, egg yolk and vanilla. Beat for 1 minute; the mixture may look a little curdled at first and will come together.
3. Whisk the flour, baking soda and salt in a separate bowl. Add to the butter mixture and mix on low just until a few streaks of flour remain. Add the chocolate and finish mixing by hand.
4. Scoop into 55 g balls, place them close together on a plate or tray, cover and refrigerate at least 1 hour and up to 72 hours.
5. Heat the oven to 175°C (350°F) with a rack in the center. Line the baking sheets with parchment.
6. Place 9 dough balls per sheet, spaced 7 cm (3 in) apart. Bake one sheet at a time for 11 to 13 minutes, until the edges are golden and set and the centers look puffed and a little underbaked. Sprinkle with flaky salt as they come out.
7. Cool on the sheet for 10 minutes, then move to a rack.

Tips for success

• Dough chilled longer than 24 hours is firm. Let the balls sit at room temperature for 10 minutes so they spread evenly.
• For rippled edges, rap the sheet on the counter twice in the last 2 minutes of baking.
• Chopped chocolate bars give pools and shards; chips hold their shape and give a more uniform cookie.

Substitutions

Egg yolk

A whole egg makes a puffier, more cake-like cookie that spreads less evenly. Reduce the discard to 70 g if you use one.

Dark chocolate

Milk chocolate or semisweet chips swap by weight; the cookie will be sweeter.

All-purpose flour

Replace 50 g with whole wheat flour for a nuttier flavor that pairs well with the sourdough tang.

Variations

Brown butter discard cookies

Brown 200 g butter, cool until soft and opaque, and use 170 g of it. Chill the dough at least 2 hours.

Rye chocolate chunk

Replace 75 g of the flour with whole rye flour for an earthy, slightly cocoa-like note.

Troubleshooting

Cookies spread into thin puddles

The butter was too soft or the dough was not chilled. Use cool butter and chill at least an hour; check that the discard was weighed, not estimated.

Cookies are cakey and pale

Too much flour or a whole egg instead of a yolk. Weigh the flour and follow the yolk-only formula.

No sourdough flavor

Fresh, mild discard and a short chill give little tang. Use discard that has been refrigerated a few days and rest the dough 24 to 48 hours.

Storage

Keep baked cookies in an airtight container at room temperature for up to 4 days. Freeze dough balls for up to 3 months and bake from frozen, adding 1 to 2 minutes.

Safety notes

Do not eat the raw dough; it contains raw egg yolk and raw flour. Contains wheat, egg, milk and possibly soy.