This is the only chocolate sourdough cookie recipe you will ever need. They're chewy, gooey, and ultra chocolatey from both cocoa powder and pools of melty chopped chocolate. Sourdough discard is a key ingredient to giving them their fudgy texture. And highly recommend a pinch of flaky salt on top for the perfect blance of flavors!
In a stand mixer, cream the butter on medium speed for one minute. It will be lighter in color and fluffier. Add sugars and cream for 2 more minutes, scraping down sides at least once. The sugar will start to dissolve into the butter, and the texture will be lighter and fluffier.
Scrape down sides and bottom of bowl. Add egg, sourdough discard, and vanilla. Mix on low speed to combine.
In another bowl, whisk together flour, salt, cocoa powder, espresso powder, baking powder. and baking soda. Add dry ingredients to mixer bowl while it is on low speed for 30 seconds. Then turn speed up to medium for 30 seconds just to combine.
Remove bowl from mixer and add chopped chocolate. Use spatula to fully combine and disperse chocolate.
Cover dough and refrigerate for 45 minutes. When time is up, preheat oven to 375 degrees F. When oven is ready, take dough out of fridge and make 55 gram dough balls.
Place 8 dough balls on a baking sheet and bake for 12-13 minutes, rotating the baking sheet when they're halfway done, and baking edges and tops are just set - they'll look slightly underbaked. They won't have all the crinkles yet, those will come as the cookies cool.
Remove from oven and sprinkle with a pinch of flaky salt each, and let cool for 5 minutes on baking sheet. They will continue to finish baking. If you'd like perfectly round cookies, place a large round pastry ring to create the perfect circles right when they are out of the oven, like this video shows.