In lg bowl, with a mixer on medium speed, beat 1 cup butter. 1/2 cup powdered sugar, and vanilla until smooth.
In a med. bowl, mix flour and baking powder.
Add to butter mixture, stir to mix then beat until well blended. Stir in pecans.
Shape dough into 1 inch balls and place about 1 in apart on buttered 12 by 15 inch baking sheet.
Bske @ 300 until cooies are pale golden brown, about 25 minutes If baking two baking sheets at once in one oven, switch their positions halfway through baking. Let cookies stand on sheets until cool enough to handle.
Place remaining 1-1/2 cups of powdered sugar in a shallow bowl. Roll warm cookies in powdered sugar to coat all over, discard remaining sugar. Set cookies on rack to cool completely.