In the bowl of a stand mixer, add softened butter and sugar. Cream them together for a few minutes until they become light and fluffy.

Add your sourdough discard, egg, and vanilla extract. Mix until combined. Scrape down the sides a few times during the mixing.

In a separate bowl, combine the flour, baking soda and salt.

Add the dry ingredients to the wet ingredients about ⅓ at a time, mixing briefly after each addition, and mix until just incorporated.

Roll into a disk and either wrap in plastic wrap or place in a bowl with a lid. Place in the refrigerator for at least 30 minutes to firm up.

Preheat the oven to 375 degrees Fahrenheit.

Prepare a baking sheet with parchment paper for easy clean up.

Place reserved white sugar in a small bowl.

Using a cookie scoop or tablespoon, scoop the dough into small balls, about 1 tablespoon in size.

Roll in the palms of your hands until a smooth ball forms.

Roll the cookie dough balls in the bowl of sugar and place on the prepared baking sheet at least 2” apart.

Using a small spoon, press into the dough ball in the center to create a well. Add about a teaspoon of jam to the center of each cookie.

Repeat until all the cookies are filled.

Place in the hot oven and bake for 10-12 minutes or until the cookies start to turn golden on the edges.

Transfer carefully to a cooling rack. Dust with powdered sugar if desired.