These sourdough butter pecan cookies solve a problem most discard cookies don't admit to having: they either spread thin and greasy, or bake up strangely cakey, because nobody accounts for the fact that discard is roughly half water. Browned butter and toasted pecans do the flavour work here, while a yolk-only egg and a proper chill hold the dough's structure together. The result is a properly chewy sourdough cookie with a crisp edge and a crackled, crinkled top, dialled in over enough batches that the troubleshooting below covers every way it can go wrong.
Toast the pecans: melt the 10g butter in a small pan over medium heat, add the chopped pecans and toast for 3-4 minutes, stirring, until fragrant and a shade darker. Tip onto a plate to cool completely — warm pecans will melt into the dough and turn it greasy.
Brown the butter: melt the butter over medium heat until it foams, then turns golden and smells nutty. Cool slightly.
Pour the granulated and brown sugars together into a large bowl. Pour the browned butter over them and beat 2 minutes with an electric mixer. The sugar will look grainy but hydrated.
Add the egg yolk and vanilla, beat another 2 minutes.
Stir in the sourdough discard by hand with a balloon whisk — no mixer, so you don't develop the gluten.
In a separate bowl, whisk the flour, baking soda, cinnamon and salt. Fold into the wet mixture until just combined.
Fold in the cooled pecans, saving a few pieces or halves to press on top.
Cover and chill for at least 4 hours.
Preheat the oven to 180°C/350°F and line a baking sheet with parchment. Weigh the dough and divide into 8 equal balls — around 65g each. Space them well apart and press a pecan on top of each if using.
Bake for 13-15 minutes, until the edges are golden and the centres are still soft. As soon as they come out of the oven, drop the baking sheet from 20 cm height onto a worktop lined with a couple of layers of kitchen towel - this will depuff the cookies and create crackly tops.
Sprinkle with flaky salt if using. Cool on the tray for 10 minutes, then transfer to a wire rack.