In the bowl of your stand mixer add the butter, brown sugar, and granulated sugar and beat to combine well. Beat until fully mixed, about 3 minutes.
Add the egg and vanilla and beat to combine, scraping down the sides as needed.
Add the sourdough starter and mix until just combined.
Sprinkle the baking powder, baking soda, and salt into the bowl. Add the flour. Mix to combine.
Add the chocolate chips and stir to combine.
Scoop a heaping tablespoon of the cookie dough onto a baking mat or parchment paper lined baking sheet. Space the cookies about 2 inches apart.
Bake until the cookies are golden brown, about 10 minutes.
Let the cookies cool on the pan for 1-2 minutes before removing to finish cooling on a wire rack.
Repeat with remaining cookie dough.
Store extra cookies in an air-tight container.
Notes
If you want less tang in these cookies, use a bubbly active starter for this recipe. If you like the tang, use your sourdough discard. If you are neutral, start by using your mature starter to see how that goes first.
Once the starter is added, it’s important not to beat it too much because you will develop the gluten in the cookies and you’ll end up with a more chewy and cakey cookie.
You can use a whole wheat sourdough starter or an all-purpose sourdough starter. The flavor will vary depending on the unique circumstances of your starter.
Store in an airtight container or freeze for up to three months.