Preheat oven to 375°F. Line two baking sheets with parchment paper.
Using a hand mixer on medium speed, beat the butter, granulated sugar, and confectioners' sugar together until smooth.
Add egg and vanilla and beat until completely incorporated, scraping down the sides of the bowl as necessary.
In a separate bowl, whisk together the flour, baking powder, and salt. Add to the egg mixture and mix until just incorporated.
Fold in pecans, making sure they are fully incorporated.
Using a 3-tablespoon cookie scoop, add dough to the lined baking sheet, leaving about 2 inches between each cookie.
Press a kitchen glass onto a damp paper towel, followed by dipping it into granulated sugar. Press the glass down onto the dough ball until the cookie is about ½-inch thick. Repeat with the remaining cookies.
Bake for 9–11 minutes, or until the tops of the cookies change to a dry look and the edges are a light golden brown.
Remove from oven and let rest before transferring to wire racks to cool completely.