In large bowl, cream butter and brown sugar until fluffy. Add eggs and vanilla; beat until smooth.
In medium bowl, combine flour and baking soda. Add dry ingredients to creamed mixture; stir until a soft dough forms. Stir in butterscotch chips and pecans.
Drop tablespoonfuls of dough 2 inches apart onto a greased baking sheet. Bake 7-9 minutes or until bottoms are lightly browned. Transfer cookies to wire racks to cool. Store in single layers between waxed paper in an airtight container.