Cream together butter, vanilla, and 1/2 cup powdered sugar until completely combined.
Add flour and nuts, stir just until it comes together.
Roll dough into 1-inch balls and place onto a cookie sheet.
Bake at 400°F for 10 to 12 minutes.
Remove from the oven and allow to cool for 1 minute, then move to a wire rack.
Allow to cookies to cool slightly. You want them warm, but not hot.
Add remaining 1/2 cup powdered sugar to a shallow bowl.
Gently roll the cookies in the powdered sugar and place back on the wire rack to finish cooling completely.
Roll completely cooled cookies in the powdered sugar one more time.
Notes
The dough may be crumbly. Mix it by hand if necessary. If the dough sticks together into a ball when you squeeze the dough, it is ready to use.
These cookies will not spread like other cookies. You can place them 1-inch apart on the cookie sheet so you can cook more at once.
These cookies will not brown like other cookies, only the bottoms will brown.
Roll the cookies in powdered sugar the first time while they are warm but not hot. Allow the cookies to cool for about 5 minutes before rolling. If the powdered sugar begins to melt and turn gummy, give the cookies another minute or so of cooling time.
Allow the cookies to cool completely before rolling a second time. The second coating of sugar is what makes these cookies look like snowballs.
You can toast the pecans first for an added layer of flavor.