Preheat the oven to 275 °F.
Line cookies sheets with parchment paper. Using an electric mixer at low speed, cream the butter and confectioner’s sugar at low speed until smooth. Beat in the vanilla. At low speed gradually add the flour. Mix in the pecans with a spatula. With floured hands, take out about 1 tablespoon of dough and shape into a crescent. Continue to dust hands with flour as you make more cookies. Place onto prepared cookie sheets. Bake for 40 minutes. Roll in additional confectioner’s sugar while still warm. Cool completed, on wire racks. Makes about 2 1/2 dozen cookies.