In a large bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt. Set to the side.
210 grams all-purpose flour, 5 grams baking soda, 2 grams baking powder, 3 grams salt
To the bowl of a stand mixer with the paddle attachment, cream the room-temperature butter, brown sugar, and white sugar at medium speed, about 2-3 minutes or until light and fluffy. This can also be done with a hand mixer. 110 grams light brown sugar, 100 grams white sugar, 70 grams unsalted butter, room tempearture
Then, add the egg, sourdough discard, creamy peanut butter, and vanilla. Mix until smooth and combined.
70 grams sourdough discard, 125 grams creamy peanut butter, 1 large egg, 4 grams vanilla extract
Gradually add the dry ingredients while mixing on low speed. Stop to scrape the sides of the bowl when necessary.
Wrap the cookie dough in plastic wrap and chill in the fridge for at least 4 hours or overnight.
Once ready, preheat the oven to 350 degrees F and line a rimmed baking sheet with parchment paper. With a cookie scoop or hands, roll a heaping Tablespoon of peanut butter cookie dough into a round ball. Roll each dough ball in the bowl of granulated sugar and place on the prepared baking sheet about 2 inches apart. I bake 12 at a time. 100 grams sugar, for rolling
Bake for 9-11 minutes, or until the cookie is cracking and the bottoms are just turning golden brown. Remove the sourdough peanut butter blossom cookies from the oven and place a Hershey Kiss in the center of each cookie.
Hershey Kisses
Gently place the chewy peanut butter cookies on a cooling rack to cool.
Once they've cooled slightly, serve them warm and enjoy!