Add powdered sugar and flour and work into butter mixture until a stiff dough has formed.
Fold in walnuts.
Shape into 1" balls.
Bake 2″ apart for 10 minutes on an ungreased cookie sheet; allow to cool for several minutes.
When they’re still slightly warm to the touch, roll in powdered sugar. If they’re too hot, the sugar will melt, but if they’re completely cooled, it won’t stick as nicely.
Allow to cool fully before storing in an air-tight container.
Refrigerate until serving. If desired, roll in powdered sugar again right before serving.
Recipe by Hell Yeah It's Vegan! at http://hellyeahitsvegan.com/mexican-wedding-cakes/