Preheat the oven to 350 degrees F—line two baking sheets with parchment paper. Set aside. In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
210 grams all-purpose flour, 6 grams baking soda, 1 grams salt
In a bowl of a stand mixer with a paddle attachment, cream together 1 stick of butter and light brown sugar, for about 2 minutes, at medium speed. Add peanut butter, sourdough discard, egg, and vanilla extract and mix on low speed until combined. 113 grams unsalted butter, softened, 210 grams light brown sugar, 250 grams peanut butter, 100 grams sourdough discard, 1 egg, 4 grams vanilla extract
Add the dry ingredients to the wet ingredients in increments of three. Mix until the flour mixture is just combined. It will be a soft dough, but shouldn't be sticky. If so, add 35 grams (1/4 cup) of flour, if needed.
With a cookie scoop or tablespoon, scoop dough, about 2 Tablespoons worth, and roll it into a smooth dough ball. Roll the small balls in the sugar and place them 2 inches apart on the cookie sheet. 100 grams white sugar, for rolling
Using a fork, gently indent the top of the cookie with the fork prongs. Rotate the cookie 90 degrees and indent again to create a crisis cross pattern.
Bake the cookies for 10-12 minutes, or until the edges are just turning golden brown. Leave the cookies on the hot baking sheet for 10 minutes and then carefully move them to a wire rack to cool completely.
Repeat with the remaining dough.
When ready to serve, spread a layer of peanut butter on the bottom of one cookie and your favorite jam or jelly on the bottom of another Sourdough Peanut Butter Cookie. Push together to create a delicious Sourdough Peanut Butter and Jelly Sandwich Cookie, serve with a cold glass of milk, and enjoy!
Peanut Butter & Jelly for center