Preheat the oven to 375 and line two baking sheets with parchment paper or a silpat mat.

Prepare two baking sheets by lining with parchment paper or a silpat mat.

In the bowl of an electric mixer, cream the butter and sugar until light and fluffy, 3-5 minutes.

Mix in the eggs until combined.

Add in the sourdough discard, cocoa, and vanilla and mix until well combined.

In a medium bowl, whisk the the flour, cornstarch, baking soda and salt together, and then mix into the dough until just combined.

Using a cookie scoop, scoop out 2 Tablespoon worth of dough directly into the powdered sugar.

Carefully roll the dough in the powdered sugar until completely coated.

Transfer the dough balls to the prepared baking sheet and space 2″ apart.

Bake for 8-10 minutes.

Allow to cool on the baking sheet for 5 minutes, then transfer to a wire rack to finish cooling.