Pre-heat oven to 350°F.
Line baking pans with parchment paper.
In a large bowl with a wooden spoon, mix butter and sugar until well combined. Add pecans and vanilla. Add flour and mix until mixture is crumbly in texture but comes together if you place about a teaspoon in your hand and make a fist.
By teaspoonfulls, shape dough into 1 1/2 inch crescents. Place on parchment paper lined cookie sheets, about 2 inches apart. Bake until edges turn slightly brown, about 12-15 minutes.
Cool on cookie sheet for one minute (If you don’t do this they’ll fall apart).
While still warm, roll in confectioner’s sugar and place on wire rack to cool. Once cool, roll cookies in sugar one more time.