Preheat oven to 350 degrees F and prepare (2) baking sheets with parchment paper
In a large mixing bowl, combine the powdered sugar, cocoa powder and salt; whisk together to combine
Add in the egg white and vanilla extract and whisk until the cookie batter becomes thick and sticky and all ingredients are fully combined and smooth
Using a spatula, fold in the semisweet chocolate chips and the chopped pecans
Allow the cookie batter to sit for 5-10 minute to slightly thicken
Using a ¼ cup or Ice cream scoop, scoop the cookie batter onto the parchment lined baking sheets spaced apart (I only fit six cookies on one sheet pan)
Bake for 11-12 minutes until the cookies are crackled on the top and the batter looks fully cooked through
Remove the cookies from the oven and allow them to cool completely before removing them from the sheet pan (they will be very soft until cooled)
Serve the cookies or store in an airtight container
Mudslide cookies are best enjoyed the day they are baked!