Preheat oven to 325 degrees. Line baking sheet with parchment paper. Set aside.
Sift together flour, baking soda and salt. Set aside.
In another bowl beat together butter, brown sugar and granulated sugar until creamy. Beat in vanilla. Beat in eggs 1 at a time.
Slowly mix in dry ingredients until well combined.
Fold in chopped Twix.
Scoop a tablespoonful of dough into your hands and roll taking care to make sure Twix pieces are mostly covered with the cookie dough. Cook 8-10 minutes or until edges start to brown and cookies are set.
Allow to cool for 2 minutes on cookie sheet. Transfer to cooling rack to cool completely.