Preheat the oven to 350 degrees and line two cookie sheets with parchment paper.
To the bowl of a stand mixer using the paddle attachment (or using a hand mixer), beat the butter and powdered sugar together about 1 minute until creamy. Add the sourdough discard and vanilla extract and whip again on medium-high speed until completely combined and the mixture looks light and fluffy. Scrape down the sides of the bowl as needed and mix again until completely incorporated.
To a small bowl whisk together finely chopped pecans (I like to give them a whirl in my blender), flour and salt. Add the dry ingredients into the bowl with the butter mixture and beat in the flour mixture until completely combined.
Scoop the dough into balls, about 25 grams (1 Tablespoon) each and place onto a baking sheet, about 12-15 cookies per baking sheet.
Bake cookies for 15 minutes. The cookies will not spread much, but will form a mound on the cookie sheet with the inside soft and tender, but baked through. Remove the cookies from the oven and let rest for about 5 minutes.
After 5 minutes roll the warm cookies in the reserved powdered sugar. Place on a baking rack or parchment paper to cool. Once the cookies are cooled roll again in powdered sugar until completely coated. Enjoy!
