Preheat oven to 375°F. Line two baking sheets with parchment paper.
In a large mixing bowl or the bowl of a stand mixer fitted with paddle attachment, cream the butter, granulated, and powdered sugars together until smooth.
Add egg and vanilla and beat until completely incorporated, scraping down sides of bowl as necessary.
Add the sifted flour, baking powder, and salt into a bowl and mix until just combined.
Stir in pecans and make sure they are fully incorporated.
Using a cookie scoop that holds 1 1/2tablespoons, scoop dough and place on the prepared baking sheet at least 2" apart.
Press a kitchen glass onto a damp paper towel and then dip it into granulated sugar. Press the glass down onto the dough ball until cookies are about 1/2 inch thick. Repeat with all cookies.
Bake 9–11 minutes or until the tops of cookies change to a dry look and the edges are a light golden brown.
Remove from oven and cool completely on wire racks.