Preheat oven to 300ºF, place parchment paper or silicon mat on your baking sheet.
In an electric mixing bowl beat together butter, sugar and vanilla on medium speed until very creamy.
In a separate bowl sift flour and baking powder, add to the butter mixture on a low speed, mix until well incorporated. Stir in pecans.
Make 1" balls with the dough and place on a baking sheet, 1 1/2" apart from each other.
Bake for 25 minutes. Let them rest for 1 minutes in a sheet and roll in the powdered sugar when the cookies are still warm. Store the cookies in the airtight container for a few days.