In a large mixing bowl, using an electric mixer, cream together the softened unsalted butter and 1/2 cup powdered sugar on medium speed until light and fluffy, about 2-3 minutes.

Beat in the vanilla extract until combined. Scrape down the sides of the bowl. Add the sourdough discard and mix on low speed until just combined. The mixture might look a little curdled; this is normal.

In a separate medium bowl, whisk together the all-purpose flour and salt.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined and a soft dough forms. Do not overmix.

Fold in the finely chopped pecans using a rubber spatula until evenly distributed.

Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes. This helps the cookies hold their shape.

While the dough chills, preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Scoop the chilled dough by rounded tablespoons and roll into 1-inch balls. Place them about 1 inch apart on the prepared baking sheets.

Bake for 10-12 minutes, or until the edges are lightly golden. The cookies will still be very soft when hot.

Let the cookies cool on the baking sheets for 5 minutes before carefully transferring them to a wire rack to cool completely. While still slightly warm, or once cooled, roll the cookies in additional powdered sugar to coat thoroughly. For an extra coating, let them cool completely and roll them in powdered sugar again.